Abstract:
A remote control is powered by multiple batteries connected in series. The remote control includes a voltage comparison circuit configured to compare a midpoint voltage from a node connecting two of the batteries to a reference voltage. The remote control is able to determine if there is a non-uniform drain rate in the batteries based on the comparison.

Description:
BACKGROUND 
     1. Technical Field 
     The present application relates to the field of managing batteries in an electronic device. The present invention relates more particularly to predicting when the batteries in a remote control will die. 
     2. Description of the Related Art 
     Television receivers and many other kinds of electronic devices are controlled by a remote control. The remote control is to be powered by batteries. As a remote control transmits control signals to the television receiver, the voltage level of the batteries eventually drops below a level that can effectively powered remote control. 
     Some television receivers monitor the voltage level of the batteries in the remote control and when the voltage level drops below a certain point the television receiver outputs an indication that the batteries in the remote control are low and should be replaced or recharged. While this can be useful to the user of the remote control, often the low battery signal is given prematurely. 
     BRIEF SUMMARY 
     One embodiment of the present application is a method for predicting the remaining useful life cycle of the batteries in a remote control. The method includes periodically sending a signal from the remote control to a television receiver indicating the current voltage level of the batteries and the remote control. The television receiver stores the voltage values in a memory. The television receiver gathers data regarding the usage of the remote control. The television receiver calculates a predicted battery life curve based on the voltage values recorded in the memory and the usage data. Based on the predicted battery life curve, the television receiver estimates a remaining lifetime of the batteries. 
     In one embodiment, the usage data includes a number of times that the remote control has transmitted control signals to the television receiver and other devices. The television receiver utilizes the voltage levels and the usage data to determine how quickly the voltage of the batteries depletes with a particular amount of use. The television receiver then determines what type of batteries are in the remote control and can predict when the batteries will go dead at the current usage rate. When the television receiver determines that the batteries will be dead within a selected threshold time, the television receiver outputs an indication on a display indicating that the user should replace or recharge the batteries before the end of the threshold time. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a block diagram of a system predicting the remaining lifetime of batteries in a remote control according to one embodiment. 
         FIG. 2  is an illustration of a home entertainment system including a television receiver that predicts the remaining lifetime of batteries and a remote control according to one embodiment. 
         FIG. 3  is a block diagram of remote control and the television receiver according to one embodiment. 
         FIG. 4  is an illustration of a residential setting including multiple television receivers and remote controls according to one embodiment. 
         FIG. 5  is a graph of the cell voltage of various batteries versus the percent of capacity discharged according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Batteries are used to power a very large variety of electronic devices. These devices include remote controls, PDAs, MP3 players, smart phones, game controllers, laptop computers, tablets, headlamps, and many more devices. As a battery discharges the battery voltage gradually decreases until the electronic device can no longer be powered by the battery. At this point the user of the electronic device will replace or recharge the battery 
     There are many types of battery cells, including lithium-ion, lead acid, Ni—Zn, Ni—Cd, NiMH, Zn/MnO 2 , etc. Each type of battery has a particular voltage when fully charged. The voltage of each type of battery follows a particular curve as the battery discharges. 
       FIG. 1  is a block diagram of a system  20 . The system  20  includes a remote control  22  and an electronic device  24  configured to be controlled by the remote control  22 . The remote control  22  includes a battery  26  coupled to a controller  28 . The controller  28  is further coupled to a wireless transceiver  30 . Electronic device  24  includes a controller  32  coupled to a wireless transceiver  34  and a memory  36 . 
     The remote control  22  controls the electronic device  24  by transmitting control signals from the transceiver  30  to the electronic device  24 . In particular, the controller  28  causes the transceiver  30  to transmit control signals according to input received from a user and instructions stored in a memory of the controller  28 . The remote control  22  is powered by the battery  26 . 
     The electronic device  24  receives the control signals from the remote control  22  and executes the commands contained in the control signals. In particular, the transceiver  34  receives the control signals transmitted by the transceiver  30  from the remote control  22 . The controller  32  of the electronic device  24  decodes the control signals and executes the instructions contained in the control signals. 
     As the remote control  22  transmits control signals to the electronic device  24 , the battery  26  gradually discharges. Each control signal transmitted by the remote control  22  depletes the battery  26  by a small amount. The accumulation of the transmission of many control signals from the remote control  22  eventually depletes the battery  26  to a point at which the battery  26  can no longer power the remote control  22 . As the battery  26  discharges, the voltage across the terminals of the battery  26  decreases. The manner in which the voltage of the battery  26  decreases is particular to the chemical type of the battery  26  as well as the particular manufacture of the battery  26 . 
     In many applications it is useful for the user of the remote control  22  to know when the battery is near the end of its life and should be recharged or replaced. For this reason, the controller  32  of the electronic device  24  executes a method for estimating a failure date of the battery  26  of the remote control  22 . 
     In one embodiment, the controller  28  of the remote control  22  periodically measures the voltage across the terminals of the battery  26 . The controller  28  then causes the transceiver  30  to transmit a battery voltage signal to the electronic device  24  including a voltage value indicating the current voltage of the battery  26 . The transceiver  34  receives the battery voltage signal and the controller  32  decodes the battery voltage signal and stores the battery voltage value in the memory  36 . Because the remote control  22  transmits a battery voltage signal periodically, the controller  32  stores each of the battery voltage values, corresponding to a particular date, in the memory  36 . The memory  36  therefore contains a database or table indicating the voltage of the battery  26  at particular dates. 
     The controller  32  of the electronic device  24  also monitors the usage of the remote control  22 . In particular, the electronic device  24  monitors how frequently the remote control  22  is used and stores this usage data in the memory  36 . The controller  32  executes an algorithm that estimates a voltage curve of the battery  26  versus the amount discharged from the battery  26 . The controller  32  then predicts, based on the voltage curve and the previous usage pattern of the remote control  22 , a failure date of the battery  26  other remote control  22 . 
     The electronic device  24  provides to the user of the remote control  22  a warning that the battery  26  of the remote control  22  should be replaced before the predicted failure date. In this way, the user of the remote control  22  can receive a relatively accurate warning that the batteries should be replaced soon. Because the predicted failure date is based on the usage pattern of the remote control  22  and the voltage values of the battery  26 , the predicted failure date takes into account how the user uses the remote control  22 . If the user uses the remote control  22  infrequently, then even in a case in which the voltage of the battery  26  is low, the battery  26  may yet have a long remaining lifetime because the user does not use the remote control very frequently. Likewise, if the user uses the remote control  22  very frequently, then even in a case in which the voltage of the battery  26  is not currently low the remaining life of the battery  26  may not be very long due to the frequent use of the remote control  22 . Thus, the electronic device  24  can output a warning to the user to replace or recharge the battery  26  before a particular date even though the voltage of the battery  26  is not currently low. 
     This provides several advantages over a system in which the electronic device  24  outputs a low battery indication when the voltage on the battery  26  drops below a particular level. In a case in which a user uses the remote control infrequently, when the voltage of the battery  26  drops below the threshold for outputting the low battery signal, the user may yet have to suffer through a low battery indication for several months before the battery actually dies. Or, alternatively, the user may prematurely replace or recharge the battery  26  when there were many months left of battery life. In a case in which a user uses the remote control very frequently, the low battery signal may come on too late for the user to replace or recharge the battery  26  before the battery  26  dies. 
     In one embodiment, the electronic device  24  includes data stored in the memory  36  corresponding to a plurality of characteristic voltage curves of many types of batteries. As the voltage on the battery  26  decreases, the controller  32  can predict what type of battery  26  is in the remote control  22  by comparing the voltage values stored in the memory  36  to the characteristic voltage curves stored in the memory  36 . In this way the controller  32  can determine whether the battery is a lithium-ion battery, a Ni—Zn battery, etc. By fitting the voltage values to one of the characteristic voltage curves, the controller  32  can predict, in conjunction with the remote control usage data, when the battery will die. 
     In one embodiment, the electronic device  24  is a television receiver configured to receive media content from a television service provider such as a satellite television provider, a cable television provider, a terrestrial broadcast television provider, etc. The television receiver  24  outputs media content such as television shows, movies, etc. on a display coupled to the television receiver  24 . The remote control  22  controls the television receiver  24 , allowing a user to change the channel on the television receiver, access and electronic programming guide, access other menu options, etc. 
     As a user uses the remote control  22 , the remote control  22  periodically transmits the battery voltage signals to the television receiver  24  as described previously. The television receiver  24  also collects remote control usage data indicating usage patterns of the remote control  22 . In one embodiment, the television receiver  24  keeps track of the number of buttons pressed on remote control  22  or the number of control signals transmitted from the remote control  22  and stores data regarding this remote control usage in the memory  36 . The controller  32  can also store data regarding usage of the remote control on particular days of the week or times a day. 
     The controller  32  of the television receiver  24  predicts a failure date of the battery  26  other remote control  22  based on the usage data, the voltage values, and characteristic curves stored in the memory  36  as described previously. When the predicted failure date is within a threshold time, the television receiver  24  outputs a message on the display indicating to the user that remote control battery  26  should be replaced or recharged before the predicted failure date. The message can indicate a specific date by which the battery should be replaced or recharged, a time range during which the battery  26  should be replaced or recharged, etc. In this manner the user of the remote control  22  is reliably notified that the battery  26  should be replaced soon. 
     Electronic device  24  can be any kind of electronic device configured to be controlled by a remote control  22 . Such devices can include a game console, a stereo system, a remote control vehicle, a television, a DVD player, a home appliance, or any other electronic device that can be controlled by a remote control. 
     The remote control  22  can be a battery-powered device other than just a remote control. For example, the battery-powered device  22  can be a remote control vehicle, a PDA, an MP3 player, a smart phone, a game controller, a laptop computer, a tablet, an automobile, a headlamp, or any other applicable device. In other embodiments the battery powered device  22  can include devices connected to AC power having battery backup, such as a fire alarm, a carbon monoxide alarm, or other suitable devices. The controller  28  of a battery powered device  22  can collect the battery voltage values, the usage pattern, and the characteristic curves and can use them to predict the failure date of the battery  26  in the same manner as described previously with respect to the electronic device  24 . 
     While the remote control  22  has been described above as having a single battery  26 , those of skill in the art will understand that the remote control  22  can include multiple batteries  26  connected in series or in parallel. The battery voltage signals transmitted from the remote control  22  can include the total voltage across a plurality of batteries  26  connected in series or the total voltage across a plurality of batteries connected in parallel. 
     In one embodiment, when the battery  26  has been replaced or recharged, the controller  32  can use the voltage values from the previous usage cycle of the remote control  22  to more accurately predict a failure date of the new or recharged battery  26  of the remote control  22 . For example, if the first several voltage values of the new battery  26  are similar to those of the previous battery, then the controller  32  can quickly generate an accurate voltage-discharge curve of the battery  26  based on the previous voltage values and usage history. Thus the controller  32  can store in the memory  36  multiple cycles of battery voltage and usage data, each cycle corresponding to the lifecycle of a battery  26  used in the remote control  22 . 
       FIG. 2  illustrates a home entertainment system  20  including a remote control  22  controlled by a user  38 , a television receiver  24 , a television coupled to the television receiver  24 , and on electronic entertainment device  42 . 
     The television receiver  24  is, for example, a television receiver for a satellite or cable television provider. The television receiver  24  receives television programming signals from the satellite or cable television provider and displays them on a television  40 . The user  38  uses the remote control  22  to control the television receiver  24  in order to display media content from a desired television channel, to operate a DVR associated with the television receiver  24 , or to perform other functions common to television receivers  24 . The remote control  22  can also directly control the television  40  and the electronic entertainment device  42 . 
     The remote control  22  is powered by a battery  26  as described previously. The remote control  22  periodically transmits the battery voltage signals to the television receiver  24 . The battery voltage signals include a voltage value indicating the voltage of the battery  26 . In one example, the remote control  22  transmits a battery voltage signal to the television receiver once each day. However, the remote control can transmit the battery voltage signal hourly, weekly, or according to any other suitable schedule. 
     In one example, the user  38  of the remote control  22  watches television or other media programs very frequently and thus uses the remote control  22  to control the television receiver  24  several hours each day. Each time that the remote control  22  performs a function, the battery  26  is discharged by a small amount. However, because the user  38  uses the remote control  22  a great deal each day, the battery  26  discharges relatively quickly. In this case the battery  26  may last only a few months or weeks due to the heavy usage of the remote control  22   
     In one example, the user  38  of the remote control watches television or other media programs infrequently, and thus uses the remote control  22  sparingly. Because the user  38  uses the remote control infrequently, the battery  26  discharges relatively slowly. In this case it is possible for the battery  26  the last several years without needing to be recharged or replaced. 
     The television receiver  24  is configured to monitor the usage pattern of the remote control  22 . The television receiver  24  stories in memory  36  data regarding the usage the remote control  22 . The television receiver  24  can accumulate data such as the number of times that the remote control transmits a control signal each day, week, or month. The television receiver  24  can also accumulate data regarding usage of the remote control to control the television receiver  24 , the television  40 , and the electronic media device  42 . In this way, the television receiver  24  can store in the memory  36  data regarding the usage pattern of the remote control  22 . 
     In one embodiment, the television receiver  24  is configured to store in the memory  36  data regarding characteristic battery voltage-discharge curves for multiple types of batteries. The battery voltage discharge curves can indicate how the voltage of each type of battery changes with respect to the percent of total discharged from the battery. 
     The television receiver  24  predicts a predicted failure date of the battery  26  based on the battery voltage values, the usage pattern data, and the characteristic battery voltage discharge curves. In particular, the television receiver  24  refers to the battery voltage values, the dates associated with the battery voltage values, and the usage pattern data stored in memory  36  and compares the data to the characteristic voltage discharge curves. The television receiver  24  then fits the data to one of the characteristic curves to determine which type of battery  26  is in the remote control  22 . Once the television receiver  24  has determined what type of battery is in the remote control  22 , the television receiver  24  continues to monitor the voltage values and usage data to fine tune a predicted voltage discharge curve for the battery  26  in the remote control  22 . The predicted voltage discharge curve provides an estimation of a date at which the battery  26  will longer be able to power the remote control  22  based on the usage pattern up to the current time. 
     When the predicted battery failure date is near, the television receiver  24  outputs a message on the television  40  indicating that the user should replace or recharge the battery  26  by a certain date or simply sometime in the near future. In past systems, a low battery message was displayed based only on the then current voltage of the battery  26 . This led to the situation in which a user  38  that uses the remote control  22  infrequently may be prompted to replace the battery  26  far ahead of the time that the battery  26  will actually fail. Because the television receiver  24 , according to principles of the present disclosure, outputs this message based on the usage pattern of the remote control and not only the voltage of the battery  26 , the message is displayed in a timely fashion such that the user is not prompted to replace the battery far ahead of the time that the battery will actually fail. Thus the user will not waste money buying new batteries more frequently than needed. Or, alternatively, the user will not waste time recharging the battery  26  more frequently the needed. 
     In one embodiment, the transceiver  30  of the remote control  22  includes both IR and RF transmitters. Thus, the remote control  22  can transmit both IR and RF control signals. In one embodiment, the transceiver  34  of the television receiver  24  includes both IR and RF receivers. The IR and RF receivers respectively receiver IR and RF control signals from the remote control  22 . 
     The television receiver  24  stores in the memory  36  data regarding the number of IR and RF control signals transmitted by the remote control  22 . The television receiver  22  can thus gather data regarding how many transitions per day are transmitted by the remote control  22 . The television receiver can compare this data to the voltage values received each day from the remote control  22  and can thus identify the change in voltage of the battery with respect to a certain number of control signals transmitted by the remote control  22 . This allows the television receiver  24  to accurately estimate a voltage—discharge curve for the battery  26 . 
     In one embodiment, the television receiver  24  can detect when the remote control  22  transmits control signals to a television  40  or the electronic media device  42 . Thus the television receiver  24  can gather total usage data of the remote control  22  and not data indicating how frequently the remote control  22  controls the television receiver  24 . This enables the television receiver  24  to make a more accurate prediction of the battery failure date. 
     In an alternative example, the remote control  22  stores data regarding the usage of the remote control  22 . This usage data can include the number of pulses transmitted by the remote control, the number functions performed by the remote control etc. The remote control  22  can transmit the usage data to the television receiver  24 . The television receiver  24  can thus use the voltage values and the usage data received from the remote control  22  to predict the failure date of the battery  26  of the remote control  22 . 
     In a further embodiment, the remote control  22  calculates the predicted failure date of the battery  26 . In this case, the remote control  22  stores the voltage values, the usage data, the characteristic discharge curves, etc. and estimates a voltage—discharge curve of the battery  26  of the remote control  22 . In other words, the remote control  22  performs the data storing and estimating functions ascribed to the television receiver  24  above. 
     While particular examples of ways to accurately estimate a failure date of the battery  26  has been described above, those of skill in art will recognize that many other methods can be used to predict a failure date of the battery  26  in light of the present disclosure. All such other ways follow from the scope of the present disclosure. 
       FIG. 3  is a block diagram of a remote control  22  and a television receiver  24  according to one embodiment. The remote control  22  includes a control circuit  28  powered by battery  26 . The remote control  22  includes a transceiver  30 , input keys  44 , a memory  46 , and a display  48  each coupled to the control circuit  28  and powered by the battery  26 . 
     The television receiver  24  includes a control circuit  32 . The television receiver  24  further includes a transceiver  34 , a memory  36 , a network I/O  48 , and AN input  50 , and AN output  52  each coupled to the control circuit  32 . 
     The control circuit  28  of the remote control  22  causes the transceiver  30  to transmit control signals to the television receiver  24 . The transceiver  30  can include IR and RF receivers and transmitters. The transceiver  30  can therefore transmit IR and RF control signals to the television receiver  24  and to other electronic devices. 
     The control circuit  28  periodically measures the voltage of the battery  26 . The control circuit  28  causes the transceiver  34  to transmit battery voltage signals to the television receiver  24 . The battery voltage signals includes voltage values indicating the voltage of the battery  26  at the time the measurement is made. Thus, the television receiver  24  periodically receives battery voltage data from the remote control  22  and the television receiver  24  stores the voltage values in the memory  36  as described previously. 
     A user  38  of the remote control  22  can operate the input keys  44  of the remote control  22  to transmit control signals to the television receiver  24 . The input keys can include standard input keys such as number keys, video playback keys such as fast-forward, reverse, pause, play, and stop, menu keys, DVR control keys, and any other suitable input keys. By pressing the input keys  44  the user  38  can cause the remote control  22  to transmit the control signals to the television receiver  24  or to other electronic devices. 
     The memory  46  includes software instructions for the operation of the remote control  22 . The control circuit  28  reads the software instructions from the memory  46  and executes the software instructions accordingly. The memory  46  can also include identification codes used for identifying the remote control  22 , for identifying particular commands sent with the control codes, and for identifying the television receiver  24  and other electronic devices. As described previously, the memory  46  can also store voltage values, remote control usage data, and characteristic battery voltage—discharge curves. 
     The display  48  of the remote control  22  can provide indications to the user  38  that the battery  26  is low and should be replaced. The display  48  can include LEDs, and LCD screen, or any other suitable components for providing notifications from the remote control  22  to the user  38 . 
     The control circuit  32  of the television receiver  24  stores data regarding the usage of the remote control  22  in the memory  36 . In one embodiment, the control circuit  32  stores, in the memory  36 , data regarding the number of control signals received from the remote control  22  by the transceiver  34 . The usage data therefore includes data regarding the number of control signals sent from the remote control  22 . 
     The memory  36  also contains data regarding characteristic battery voltage-discharge curves for the various chemical types of batteries. The memory  36  therefore includes voltage-discharge curves for lithium-ion batteries, lead acid batteries, N—Zn batteries, Ni—Cd batteries, NiMH batteries, and Zn/MnO 2  batteries. 
     As described previously, the television receiver  24  predicts a failure date of the battery  26  based on the battery voltage values, the usage pattern data, and the characteristic battery voltage discharge curves. In particular, the television receiver  24  refers to the battery voltage values, the dates associated with the battery voltage values, and the usage pattern data stored in memory  36  and compares these data to the characteristic voltage discharge curves. The television receiver  24  then fits the data to one of the characteristic curves to determine which type of battery is in the remote control  22 . Once the television receiver  24  has determined what type of battery is in the remote control  22 , the television receiver  24  continues to monitor the voltage values and usage data to fine tune a predicted voltage discharge curve for the battery  26  in the remote control  22 . The predicted voltage discharge curve provides an estimation of a date at which the battery  26  will longer be able to power the remote control  22  based on the usage pattern up to the current time. When the predicted battery failure date is near, the television receiver  24  outputs a message on the television  40  via the AN output  52  indicating that the user should replace or recharge the battery  26  by a certain date or sometime in the near future. 
     In one embodiment the control circuit  28  of the remote control  22  predicts a failure date of the battery  26  based on the battery voltage values, the usage pattern data, and the characteristic battery voltage discharge curves stored in the memory  46 . In other words, the remote control  22  can perform the functions ascribed to the control circuit  32  of the television receiver  24  in calculating a failure date of the battery  26 . The remote control  22  can transmit to the television receiver  24  a signal indicating the predicted failure date of the battery  26 . The television receiver  24  can then cause the television  40  to display an indication of the failure date to the user. Alternatively, the display  48  of the remote control  22  can display an indication of the predicted failure date of the battery and/or a message indicating that the user should replace the battery  26 . 
       FIG. 4  is an illustration of a residential setting including two television receivers  24   a  and  24   b , two remote controls  22   a  and  22   b , and two televisions  40   a  and  40   b . Two users  38   a  and  38   b  are operating the remote controls  22   a  and  22   b  respectively. The television receivers  24   a  and  24   b  are connected by network connection  60 . A satellite receiver  62  provides media content to the television receivers  24   a  and  24   b.    
     The television receivers  24   a  and  24   b  receive battery voltage signals from the remote controls  22   a  and  22   b . In particular, the television receiver  24   a  receives battery voltage signals from the remote control  22   a . The television receiver  24   b  receives battery voltage signals from the remote control  22   b . The television receiver  24   a  records usage data regarding the usage of the remote control  22   a . The television receiver  24   b  records usage data regarding the usage of the remote control  22   b.    
     It is possible that the remote controls  22   a  and  22   b  can be switched such that the remote control  22   b  controls the television receiver  24   a  and the remote control  22   a  controls the television receiver  24   b . The remote controls  22   a  and  22   b  transmit with their control signals and battery voltage signals an identification code that identifies the remote control  22   a  or  22   b . The television receivers  24   a  and  24   b  can store usage data regarding each remote control  22   a  and  22   b . Furthermore, the television receivers  24   a  and  24   b  can share with each other, via a network connection  60 , the voltage values and usage data for each of the remote controls  22   a  and  22   b . In this way, the television receivers  24   a  and  24   b  can each make accurate estimations of voltage battery failure dates for each of the remote controls  22   a  and  22   b . Each of the television receivers  24   a  and  24   b  can display a battery replacement message that corresponds to the remote control  22   a  or  22   b  currently controlling that television receiver. 
       FIG. 5  is graph illustrating the characteristic battery voltage discharge curves for the different types of batteries. In particular, the graph of  FIG. 5  shows the voltage across different types of batteries against the percentage of capacity discharged. It is known that the voltage of a battery cell is determined by the specific chemistry of the battery. Furthermore, the rate of change in the voltage of the battery as the battery discharges is different for each type of battery. For example, a lithium ion battery cell has a higher voltage than most other cells and also experiences a sharper change in the voltage at the beginning and end of its life cycle than many other kinds of batteries. Lead-acid, Nickel-Zinc, Nickel-Cadmium, Nickel-metal-hydride, and Zinc-Magnesium oxide batteries all have different voltages and decay curves. Data representing these characteristic voltage-discharge curves can be saved in the memory  36  of the television receiver  24 . The characteristic voltage-discharge curves can be used to predict the type of battery  26  in the remote control  22 . The characteristic voltage—discharge curves can also be used to estimate a voltage discharge curve for the particular battery  26  in the remote control  22  as described previously. 
     The various embodiments described above can be combined to provide further embodiments. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.