Abstract:
Described is a method wherein a computer terminal is coupled to a power supply through a docking arrangement. The docking arrangement includes a protection circuit. A current supplied to the computing terminal is detected. When the current is greater than a predetermined value, the computer terminal is decoupled from the power supply. After the computer terminal is decoupled from the power supply, the computer terminal is recoupled to the power supply, and the method repeats beginning with detecting the current supplied to the computing terminal.

Description:
BACKGROUND  
       [0001]     In a conventional computing network, a plurality of components may be coupled to a common device for power management and/or data transfer. For example, the common device may be a cradle which receives one or more mobile computing terminals. Upon connection to the cradle, the terminal may receive power therefrom (e.g., charge a battery) and communicate with a network device (e.g., a server) coupled thereto. However, upon connection or during operation, one or more of the terminals may experience a short circuit causing the remaining terminals and/or the cradle to malfunction. The short circuit results in delivery of an excessive amount of power to the shorted terminal, inhibiting operation of the remaining terminals. Also, the excessive amount of energy may generate a great deal of heat, potentially resulting in a fire or an explosion.  
         [0002]     A conventional method of protecting against the short circuit involves terminating power delivery to each of the terminals once the short circuit is detected. For example, when a terminal short circuits, the cradle will terminate power delivery to all of the terminals connected thereto. This may interrupt operation (e.g., data transfer, charging) of the terminals which did not short circuit. A user must manually reset the cradle and correct the short circuit to reestablish power delivery to the terminals. Thus, there is a need for a system which may experience the short circuit without interrupting operation of the terminals and does not require user intervention.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention relates to a method wherein a computer terminal is coupled to a power supply through a docking arrangement. The docking arrangement includes a protection circuit. A current supplied to the computing terminal is detected. When the current is greater than a predetermined value, the computer terminal is decoupled from the power supply. After the computer terminal is decoupled from the power supply, the computer terminal is recoupled to the power supply, and the method repeats beginning with detecting the current supplied to the computing terminal. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0004]      FIG. 1  shows an exemplary embodiment of a system according to the present invention;  
         [0005]      FIG. 2  shows an exemplary embodiment of a docking device and a terminal according to the present invention;  
         [0006]      FIG. 3   a  shows an exemplary embodiment of a timing diagram according to the present invention;  
         [0007]      FIG. 3   b  shows another exemplary embodiment of a timing diagram according to the present invention; and  
         [0008]      FIG. 4  shows an exemplary embodiment of a method according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0009]     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are provided with the same reference numerals. Although, the present invention will be discussed with reference to a computing network, it should be understood that the present invention may be applied to any system which includes a plurality of devices sharing a common power source.  
         [0010]      FIG. 1  shows an exemplary embodiment of a system  7  according to the present invention. The system  7  may include a network computing device (e.g., a server  10 ) coupled to a docking device  20  (e.g., a cradle) which receives one or more wireless computing terminals  30 ,  32 ,  34 ,  36 . Although, the network computing device is shown as the server  10 , those of skill in the art will understand that the system  7  may, alternatively or additionally, include one or more further computing devices coupled to the docking device  20 . For example, the further computing device may include, but is not limited to, a personal computer, an access point, a switch, etc. In this manner, the docking device  20  may be coupled to and access a communications network (e.g., LAN, WAN, WLAN, WWAN, etc.).  
         [0011]     The server  10  may communicate with the docking device  20  via a wired or wireless connection therebetween. In one embodiment, the server  10  is coupled directly to the docking device  20 . In another embodiment, the server  10  communicates with the docking device  20  via the communications network and any devices therein (e.g, switches, routers, hubs, etc.). The server  10  may be coupled to a database which may be accessed by the docking device  20  and/or the terminals  30 - 36 . For example, the terminals  30 - 36  may synchronize with the server  10  and each other by communicating with via the docking device  20 . Also, the server  10  may access data stored in the docking device  20  and/or the terminals  30 - 36 , and vice-versa.  
         [0012]      FIG. 2  shows an exemplary embodiment of the docking device  20  and the terminal  30 . Those skilled in the art will understand that the terminals  32 - 36 , along with any further terminals, may contain substantially similar architectures to that of the terminal  30 . The terminal  30  may be any computing device which can be coupled to the docking device  20 . For example, the terminal  30  may be, but is not limited to, a portable barcode scanner, a PDA, a cell phone, a laptop, etc.  
         [0013]     The terminal  30  includes a processor  33  which controls operation thereof. The processor  33  may function as a conventional processor/controller by accessing instructions/data stored on a memory of the terminal  30 . The processor  33  and other components of the terminal  30  receive power from a first power supply  35 . In one embodiment, the first power supply  35  is a battery which may be rechargeable or replaceable. For example, when the terminal  30  is coupled to the docking device  20 , the terminal  30  may operate using power derived from the docking device and, optionally, recharge the battery. When not coupled to the docking device  20 , the terminal  30  derives power therefrom (e.g., discharges the battery).  
         [0014]     According to the present invention, the terminal  30  further includes an attachment arrangement  31  for coupling to the docking device  20 . In one embodiment, the attachment arrangement  31  is a port which receives a cable  37  (e.g., USB, serial, Ethernet, etc.) that is further connected to the docking device  20 . In another embodiment, the attachment arrangement  31  is one or more electrical leads which may directly contact corresponding leads on the docking device  20 . In any embodiment, the attachment arrangement  31  allows the terminal  30  to communicate with the docking device  20 . That is, power (e.g., current) and/or data signals may be transmitted from and received by the terminal  30  using the attachment arrangement  31 . Thus, the terminal  30  may communicate with the server  10  when coupled to the docking device  20 .  
         [0015]     As shown in  FIG. 2 , the docking device  20  may include a docking arrangement  22 , a communications arrangement  24 , a second power supply  26 , and a protection circuit  28 . In one embodiment, the docking arrangement  22  is a further port which receives the cable  37  connected to the attachment arrangement  31  of the terminal  30 . In another embodiment, the docking arrangement  22  is the corresponding leads which engage the electrical leads of the terminal  30 . As understood by those of skill in the art, the docking device  20  may include a predetermined number of docking arrangements  22  for receiving one or more terminals  30  and/or further electrical devices. Thus, the docking arrangements may be the same as the docking arrangement  22  (e.g., receive the same cable  37 ) or may vary from one to the other. For example, in the embodiment shown in  FIG. 1 , the docking device  20  would include at least four docking arrangements  22 . In any embodiment, the docking arrangement  22  may further include an indicator (e.g., a light emitting diode (“LED”), a speaker, etc.) which represents that the terminal  30  has been coupled thereto. Further, the docking arrangement  22  may include one or more terminal housings for holding each of the terminals  30 - 36  when coupled to the docking device  20 .  
         [0016]     The communications arrangement  24  of the docking device  20  may be a hardware port (e.g., USB, serial, Ethernet, etc.) which provides for a connection to the server  10  and/or any device in the communications network. In another embodiment, the communication arrangement  24  is a transceiver which provides a wireless connection to the server  10  or the communications network. In a further embodiment, the docking device  20  may not include the communications arrangement  24 , but acts simply as a charger for the power supply  35  of the terminal  40 .  
         [0017]     The docking device  20  may further include the second power supply  26  may be a conventional power source (e.g., a battery) which supplies power to the components of the docking device  20  and, optionally, the terminals  30 - 36  coupled to the docking device  20 . As understood by those of skill in the art, the second power supply  26  may be the battery which is rechargeable and/or replaceable. In another embodiment, the second power supply  26  may be an AC/DC adapter for connection to a conventional power source (e.g., a line voltage). In this embodiment, the docking device  20  may derive power from the power outlet when coupled thereto, but may derive power from the battery when not coupled to the power outlet. Furthermore, when the docking device  20  is coupled to the power outlet, the second power supply  26  may be charged. As described above, the terminal  30  is coupled to the docking device  20 , the terminal  30  may derive power from the second power supply  26 .  
         [0018]     According to the present invention, the docking device  20  further includes the protection circuit  28  which may include, for example, a microprocessor, one or more integrated circuits, a memory, a voltage and/or current sensor, etc. Alternatively, the protection circuit  28  may be implemented as one or more software modules. The protection circuit  28  monitors the connection, and in particular, the transfer of power (e.g., current and/or voltage) between the docking device  20  and the terminal  30 , which will be described below. The protection circuit  28  may further monitor a power transfer between the docking device  20  and the server  10 . In this manner, the protection circuit  28  may further include a conventional surge protector for preventing power surges between the docking device  20  and the terminal  30 , and between the docking device  20  and the server  10 . The surge protector may be comprised of, for example, metal oxide varistors (“MOVs”) and gas discharge arrestors.  
         [0019]      FIG. 3   a  shows an exemplary embodiment of a timing diagram of a power control process  300  according to the present invention. In the process  300 , the protection circuit  28  of the docking device  20  monitors a first power signal (“FPS”)  305  and a second power signal (“SPS”)  310 . The FPS  305  may represent an “ENABLE” signal to a power generation circuit. The signal is either a request that power continue to be generated (e.g., a solid HIGH) or that the power generation circuit retry initiating a generation of power (e.g., a TRANSITION from LOW to HIGH). The SPS  310  may represent a feedback signal indicating whether power is successfully applied to the terminal  30 .  
         [0020]     In Phase I, the FPS  305  is at a first value  315  indicating that power is being supplied to the terminal  30 . As described above, the power may be supplied to the terminal  30  via the docking arrangement  22  upon coupling of the terminal  30  to the docking device  20 , while the terminal  30  is coupled to the docking device  20 , or at any time which the terminal  30  is deriving power from (or communicating with) the docking device  20 . During the Phase I, the terminal  30  is in a first state (e.g., normal operation—data transfer, charging, etc.) and consuming power from the docking device  20  at a second value  320 . Thus, while the SPS  310  remains at the second value  320 , the protection circuit  28  recognizes that the terminal  30  is in the first state. Also, as shown in Phase I, the SPS  310  changes (e.g., drops) to a third value  325  which may indicate that the terminal  30  is in a second state (e.g., has short circuited). When in the second state, the terminal  30  may draw an excessive amount of current from the docking device  20 , and, as a result, the remaining terminals  32 - 36  coupled to thereto may lose power inhibiting present (e.g., data transfer) and future operation (e.g., takes longer to charge, may not be ready for use).  
         [0021]     At a first predefined time (e.g., a first checkpoint  330 ), the protection circuit  28  assesses the SPS  310 . As shown in  FIG. 3   a , at the first checkpoint  330 , the SPS  310  remains at the third value  325  indicating that the terminal  30  is in the second state. In response to detection of the third value  325 , the protection circuit  28  terminates the delivery of power to the terminal  30 . As shown in Phase II, which begins after the first checkpoint  330 , the protection circuit  28  changes the FPS  305  to a fourth value  335  (e.g., zero). In this manner, the terminal  30  may no longer draw power from the docking device  20 . Thus, the remaining terminals  32 - 36  coupled to the docking device  20  may continue operation(s) and drawing power therefrom.  
         [0022]     As further seen in Phase II, after the first checkpoint  330 , the protection circuit  28  maintains the FPS  305  at the fourth value  335  for a first duration  340  (e.g., 100 ms). In this manner, power is not being supplied to the terminal  30  for the first duration  340 . After expiration of the first duration  340 , the protection circuit  28  may change the FPS  305  back to the first value  315  for a second duration  345  (e.g., 200 ms). Thus, the protection circuit  28  is again supplying power to the terminal  30 .  
         [0023]     At a second predefined time (e.g., a second checkpoint  350 ) during or at an expiration of the second duration  345 , the protection circuit  28  reassesses the SPS  310 . As shown in  FIG. 3   a , at the second checkpoint  350 , the SPS  310  remains at the third value  325  indicating that the terminal  30  is in the second state. Upon detecting the third value  325 , the protection circuit  28  returns the FPS  305  to the fourth value  335  for a third duration (e.g., 600 ms)  355 , as shown in Phase III.  
         [0024]     In Phase III, the third duration  355  is longer than the first duration  340 , because the terminal  30  has not returned to the first state. Thus, the protection circuit  28  provides more time for the terminal  30  to return to the first state. After the third duration  355  has expired, the protection circuit  28  returns the FPS  305  to the first value  315  for a fourth duration  360  (e.g., 200 ms), supplying power to the terminal  30 .  
         [0025]     At a third predefined time (e.g., a third checkpoint  365 ) during or at an expiration of the fourth duration  360 , the protection circuit  28  reassesses the SPS  310 . As shown in  FIG. 3   a , at the third checkpoint  365 , the SPS  310  remains at the third value  325  indicating that it remains in the second state. Upon detecting the third value  325 , the protection circuit  28  returns the FPS  305  to the first value  315  for a fifth duration (e.g.,  25  s)  370 , as shown in Phase IV.  
         [0026]     In Phase IV, the fifth duration  370  is longer than the third duration  355 , because the protection circuit  28  is providing more time for the terminal  30  to return to the first state. After the fifth duration  370  has expired, the protection circuit  28  returns the FPS  305  to the first value  315  for a sixth duration  375  (e.g., 200 ms), supplying power to the terminal  30 .  
         [0027]     At a fourth predefined time (e.g., a fourth checkpoint  375 ) during or at an expiration of the sixth duration  375 , the protection circuit  28  reassesses the SPS  310 . As shown in  FIG. 3   a , at the fourth checkpoint  375 , the SPS  310  remains at the third value  325  in the second state. If the terminal  30  has not returned to the first state after the fourth checkpoint  375 , the protection circuit  28  may continue with a plurality of further checkpoints and/or provide an indication (e.g., via LED, speaker, message to the server  10 , etc.) that the terminal  30  remains in the second state. The indication may represent that the docking device  20  will no longer supply power to the terminal  30  until, for example, the user manually intervenes (e.g., resets the docking device  20 ).  
         [0028]      FIG. 3   b  shows another exemplary embodiment of the timing diagram according to the present invention. In  FIG. 3   b , at the first checkpoint  330 , the protection circuit  28  detects the third value  325  of the SPS  310  and determines that the terminal  30  is in the second-state. In response, the protection circuit  28  performs the actions described above with respect to Phase II. At the second checkpoint  350 , the protection circuit  28  reassesses the SPS  310  and detects the second value  320  indicating that the terminal  30  has returned to the first state. Thus, the protection circuit  28  may maintain the FPS  305  at the first value  315  while continually reassessing the SPS  310  at predetermined intervals (e.g., every 100 ms). If, during one of the predetermined intervals the protection circuit  28  detects that the SPS  310  is at the third value  325 , the protection circuit  28  may initiate the process  300  described above beginning with Phase II (e.g., changing the FPS  305  to the fourth value  335  for the first duration  340 ).  
         [0029]     As understood by those of skill in the art, various modifications may be made to the power control process  300  described above. For example, each of the durations may be equal to or vary with respect to one another. Also, the process  300  may utilize one or more checkpoints, and is not limited to four. Further, each of the values may be preprogrammed and known by the protection circuit  28  prior to deployment of the docking device  20 . Alternatively, the protection circuit  28  may be programmed to recognize a predefined change of the SPS  310  from the second value  320  to the third value  325 , and respond with a further predefined change of the FPS  305  from the first value  315  to the fourth value  335 . Also, at any time during the process  300 , the docking device  20  may provide the indication to the user that the terminal  30  is in the second state. That is, the user may intervene before the process  300  has been completed.  
         [0030]      FIG. 4  shows an exemplary embodiment of a method  400  according to the present invention. The method  400  may be initiated upon coupling the terminal  30  to the docking device  20  or while the terminal  30  is connected thereto and in operation (e.g., charging, transferring data, etc.). In step  410 , the protection circuit  28  initiates the first checkpoint  330  to assess the SPS  310 , and, in particular, to determine whether the SPS  310  is at the second value  320 . If the terminal is in the first state (e.g., SPS  310  is at the second value  320 ), the protection circuit  28  may continuously reassess the SPS  310  continuously or after each predetermined interval (e.g., 100 ms), and initiate the first checkpoint  330  upon detecting the predefined change of the SPS  310  from the second value  320  to the third value  325 .  
         [0031]     In step  412 , the SPS  310  is not at the second value  320 , so the protection circuit  28  changes the FPS  305  to the fourth value  335 , thereby terminating the supply of power to the terminal  30 . The fourth value  335  may be zero or a negligible amount which would allow the docking device  20  to continue supplying power to the remaining terminals  32 - 36  coupled thereto. As described above, the termination of power may be for the first duration  335 .  
         [0032]     In step  413 , the protection circuit  28  changes the FPS  305  to the first value  315 , thereby supplying power to the terminal  30 . The first value  315  may be any non-zero value which would allow the terminal  30  to operate (e.g. charge, data transfer, etc.) while in the first state. As described above, the FPS  305  may be maintained at the first value  315  for the second duration  345  which may be enough long to allow the terminal  30  to begin operating (e.g., switch to the first state).  
         [0033]     In step  414 , the protection circuit  28  initiates the second checkpoint  350  to determine whether the SPS  310  is at the second value  320 . If the terminal  30  is in the first state, the protection circuit  28  may continuously reassess the SPS  310  after each predetermined interval (e.g., 100 ms). If the SPS  310  is not at the second value  320 , the terminal  30  remains in the second state.  
         [0034]     In step  415 , the SPS  310  is not at the second value  320 , so the protection circuit  28  changes the FPS  305  to the fourth value  335 , thereby terminating the supply of power to the terminal  30 . As described above, the termination of power after the second checkpoint  350  may be for the third duration  335  which may be equal to or longer than the first duration  340 .  
         [0035]     In step  416 , the protection circuit  28  changes the FPS  305  to the first value  315  re-supplying power to the terminal  30 . As described above, the FPS  305  may be maintained at the first value  315  for the fourth duration  360 . Preferably, the fourth duration  360  is equal to the second duration  345 , thereby preventing a drain of the power supplied to the remaining terminals  32 - 36  coupled to the docking device  20 .  
         [0036]     In step  417 , the protection circuit  28  initiates the third checkpoint  365  to determine whether the SPS  310  is at the second value  320 . If the terminal is in the first state, the protection circuit  28  may continuously reassess the SPS  310  after each predetermined interval (e.g., 100 ms). If the SPS  310  is not at the second value  320 , the terminal  30  remains in the second state.  
         [0037]     In step  418 , the SPS  310  is not at the second value  320 , so the protection circuit  28  changes the FPS  305  to the fourth value  335 , thereby terminating the supply of power to the terminal  30 . As described above, the termination of power after the third checkpoint  365  may be for the fifth duration  370  which may be equal to or longer than the third duration  340 .  
         [0038]     In step  420 , the protection circuit  28  changes the FPS  305  to the first value  315  re-supplying power to the terminal  30 . As described above, the FPS  305  may be maintained at the first value  315  for the sixth duration  375 . Preferably, the sixth duration  375  is equal to the second duration  345  and the fourth duration  360 , thereby preventing a drain of the power supplied to the remaining terminals  32 - 36  coupled to the docking device  20 .  
         [0039]     In step  422 , the protection circuit  28  initiates the fourth checkpoint  375  to determine whether the terminal  30  is in the first state, and in particular, whether the SPS  310  is at the second value  320 . If the terminal  30  is in the first state, the protection circuit  28  may continuously reassess the SPS  310  after each predetermined interval (e.g., 100 ms).  
         [0040]     If the SPS  310  is not at the second value  320  after the fourth checkpoint  375 , the protection circuit  28  may, as shown in  FIG. 4 , return to the third checkpoint  365  (step  417 ) for as long as the SPS  310  is not at the second value  320 . In another embodiment, the protection circuit  28  may re-initiate the method  400  beginning at the first checkpoint  330  (step  410 ). In a further embodiment, the protection circuit  28  may provide an indication (e.g., LED, speaker, message to the server  10 ) to the user that the terminal  30  remains in the second state. In this embodiment, the docking device  20  may not allow the terminal  20  to draw power therefrom until the user manually performs a predefined action (e.g., resets the docking device  20 ).  
         [0041]     Those of skill in the art will understand that several advantages for power delivery to computing terminals are provided by the present invention. For example, the termination of power delivery to a short circuited terminal prevents a build-up of heat generated by the short circuit, which could potentially result in a fire or an explosion. Further, by terminating the power delivery to only the short circuited terminal, the remaining terminals connected to the docking device may continue operation (e.g., data transfer to server/communications network, charging, etc.).  
         [0042]     In the preceding specification, the present invention has been described with reference to specific exemplary embodiments thereof. However, it will be evident to those skilled in the art that various modifications may be made without departing from the broadest spirit and scope of the present invention as set forth in the following claims. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.