Patent Abstract:
The present invention is capable of displaying remaining electric current of a battery by compensating leakage current of a system and self-discharge current of the battery by using a system leakage current timer for compensating leakage current of the system, self-discharge timer of the battery for compensating self-discharge current of the battery. Hence, a user can properly manage remaining current of the battery because an accurate remaining current of the battery is displayed.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and a method for compensating leakage current and battery self-discharge, and more particularly, a system having such an apparatus and method. 
     2. Background of the Related Art 
     FIG. 1A illustrates a system, e.g., notebook computer,  50 - 1  having a recess for receiving a battery pack  40  and input  20  for receiving the voltage from an AC adapter. FIG. 1B illustrates a circuit diagram for detecting the remaining electric current of a battery. The battery pack  40  includes a battery  2 , a resistor R and an electric current counter  1 . When the battery is charged or discharged, an electric current flows to the resistor R and the current counter  1  measures the electric voltage generated in proportion to the electric current flowing through the resistor R. The output of the counter  1  is inputted to a micro-controller to detect the remaining electric current of the battery  2  by using the measured electric voltage. 
     However, such a circuit has various disadvantages. For example, the notebook uses a minute mA of electricity as stand-by electricity for operation of a control circuit when the system is turned OFF, resulting in a leakage current. The circuit can detect remaining electric current in the range of 10 mA. However, the minute mA of the stand-by electricity is too small to detect. For example, when a system is off after installing a charged battery on the system, the capacity of the battery decreases in accordance with the passage of time due to leakage current of the system. Further, the circuit cannot detect the self-leakage of the battery over time, whether the battery is connected or installed to the system. 
     The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter. 
     It is an object of the present invention to compensate for leakage current. 
     It is another object of the present invention to compensate for self discharge. 
     It is a further object of the present invention to accurate manage the remaining battery power. 
     It is an object of the present invention to provide a method for compensating leakage current of a system which is capable of managing remaining capacity of a battery by compensating leakage current of the system and the self-discharge of the battery connected to the system and displaying the remaining electric current of the battery on a gauge circuit. 
     To achieve the object, the method for compensating leakage current of the system of the present invention comprises judging process which judges the charge/discharge state of the battery and whether the battery is connected to the system, setting process which adds self-discharge of the battery to the leakage electric current of the system and sets the added values when the battery is connected to the system and the system is OFF, and compensating process which compensates the set self-discharge of the battery and the leakage electric current of the system by using a timer. 
     The present invention can be also achieved in a whole or in parts by a method for compensating leakage current of a system, comprising judging whether a battery is charged/discharged and the battery is connected to a system; setting leakage current of the system after adding leakage current of the system when the battery is connected to the system and the system is off; and compensating the added setting leakage current of the system by using a timer. The judging process includes the steps of: (a) detecting generation of interrupt which compensates leakage current of the system; (b) detecting state conversion of a current count which counts current used inside of the system when interrupt is not generated; and (c) setting self-discharge current of the battery when the battery is converted into discharge state. The judging process also includes the step of setting state for making setting leakage current of the system and self-discharge current of the battery not be generated when the battery is converted into charge state in the state conversion of the current count. 
     The setting process includes the steps of: (a) judging whether the battery is separated from the system in order to decide compensation value of self-discharge current of the battery; (b) judging whether leakage current of the system is detected when the battery is connected to the system; and (c) setting self-discharge current of the battery when the battery is separated from the system. 
     The compensating process includes the steps of: (a) judging whether the added self-discharge current is set when the interrupt occurs; (b) compensating self-discharge current of the battery by using the timer when value of the self-discharge current is set in the judging step; and (c) compensating the setting leakage current of the system by using the timer when the added leakage current of the system is set in the judging step. 
     The judging process may also includes the step of: setting self-discharge current of the battery when the battery is converted into discharge state, the battery is separated from the system, and leakage current of the system is not detected. 
     The present invention can be also achieved in a whole or in parts by a method for compensating leakage current of a system, comprising: judging whether a battery is charge/discharge state and is connected to the system; judging whether the battery is separated from the system in order to decide compensation value of self-discharge current of the battery; judging whether leakage current of the system is detected when the battery is connected to the system; setting self-discharge current of the battery and leakage current of the system after adding them separately when the battery is connected to the system and the system is off; compensating the setting self-discharge current of the battery by using a timer when self-discharge current is set in the setting process; and compensating the setting leakage current of the system by using the timer when leakage current of the system is set in the setting process. 
     The setting process includes the step of: setting self-discharge current of the battery when the battery is separated from the system. The judging process for judging whether the battery is connected to the system includes the steps of: (a) detecting interrupt which compensates self-discharge current of the battery and leakage current of the system; (b) detecting state conversion of the current count which counts current used inside of the system when the interrupt is not detected in the detecting step; and (c) setting self-discharge current of the battery when the battery is converted into discharge state in the state conversion of the current count. 
     The method for compensating leakage current of the system includes the step of setting self-discharge current of the battery when the battery is converted into discharge state, the battery is separated from the system, and leakage current of the system is not detected. The setting process includes the step of: setting state for making self-discharge current of the battery and leakage current of the system not be generated when the battery is converted into charge state. 
     The present invention can be achieved in a whole or in parts by an apparatus comprising: a battery pack for providing a power source; and a system for performing a prescribed function and operation to achieve a prescribed result, the system having a device that outputs one of a first voltage when the battery pack is coupled to the system and an external power source is not coupled to the system, a second voltage when the battery pack is not coupled to the system and the external power source is not coupled to the system, and a third voltage when the external power source is coupled to the system, wherein said battery pack includes a micro-controller detecting the first, second and third voltage levels to determine such conditions. 
     The present invention can be achieved in a whole or in parts a system for performing a prescribed function and operation to achieve a prescribed result, the system having a device, which includes: a resistor coupled for receiving a stand-by voltage; a transistor coupled to the resistor for receiving an output of an adapter; and a diode coupled to the transistor in parallel, wherein a voltage at a node connection between the transistor and resistor is indicative of at least one of application of stand-by voltage and output of the adapter. 
     The present invention can be achieved in a whole or in parts by a battery pack comprising: a battery; a micro-computer for compensating for leakage current and self-discharge of the battery; and a current counter that indicates discharge or charge of the battery. 
     The present invention can be achieved in a whole or in parts by a method for operating a battery pack having a battery for coupling to a system, comprising: detecting a change in the charge of the battery; determining a self-discharge of the battery; determining a leakage current of the battery; and compensating for at least one the change in the charge of the battery, self-discharge of the battery, and the leakage current. 
     The present invention can be achieved in a whole or in parts by a system for performing a prescribed function and operation to achieve a prescribed result, the system having a device, which includes: a first resistor coupled for receiving an output of an adapter; and a second resistor coupled to the first resister in series, wherein a voltage of a serial connection node is indicative of a connection to the adapter. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
     FIG. 1A illustrates a notebook computer; 
     FIG. 1B illustrates a circuit diagram for detecting the remaining electric current of a battery; 
     FIG. 2A illustrates an apparatus for detecting whether the battery pack is installed or connected to the system and whether AC power is connected to the system; 
     FIG. 2B is an alternative embodiment of FIG. 2A; 
     FIG. 3A illustrates a detailed schematic of the battery pack; 
     FIG. 3B illustrates the details of the micro-controller of FIG. 3A; and 
     FIGS. 4A and 4B illustrate the method for compensating or accounting for the self-discharge and the leakage current. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 2A illustrates an apparatus for detecting whether the battery pack  40  is installed or connected to the system  50 - 1  and whether AC power is connected to the system. The battery pack  40  includes a micro-controller  40 , resistors R 1  and R 2 . The resistors R 1  and R 2  are coupled between a voltage VCB of the battery and ground to serve as a voltage divider, and are coupled to the micro-controller  30  such that the micro-controller can detect a voltage level at a connection node P between the battery pack  40  and the system  50 - 1 . 
     The system includes a resistor R 3  coupled to a stand-by voltage VSB provided from the output of the DC/DC converter. The system further includes a diode D and a transistor Q coupled in parallel to each other and serially between the connection node P and ground. As shown therein, the transistor Q is activated by an output voltage Vcc of the AC adapter. 
     When the system uses the battery of the battery pack  40  and while the AC adapter is not connected to an external source, the DC/DC converter outputs a stand-by voltage VSB of approximately 3.3V based on the the voltage VCB of the battery. However, when the AC adapter is connected to an external source, the AC adapter outputs a voltage Vcc of approximately 16V, 19V or 24V, depending on the type of the AC adapter. In such a case, the stand-by voltage VSB provided from the DC/DC converter is approximately 5V. 
     When the AC adapter is not connected to a power source and the battery pack  40  is installed or connected to the system  50 - 1 , the transistor Q is turned off. Further, a stand-by voltage VSB of approximately 3.3V is applied. In such a case, the connection node P exhibit a high voltage, which indicates to the micro-controller  30  that the AC adapter is not connected, but the battery pack  40  is installed or connected to the system. 
     When both the AC adapter is not connected to the power source and the battery pack  40  is not installed or connected, the connection node P is floating, which is classified as a medium level. Such a state indicates to the micro-controller  30  that the both the AC adapter and battery pack  40  are not connected. 
     When the AC adapter is connected, the transistor Q is turned on, and pulls the connection node P to ground or a low level. Such low level indicates to the micro-controller  30  that the AC adapter is connected. 
     FIG. 2B is an alternative embodiment, which differs from FIG. 2A in that the transistor Q and the diode D are replaced with a resistor R 4 , and the resistor R 3  is coupled to the output from the AC adapter. For the medium level, FIGS. 2A and 2B operates the same to indicate to the micro-controller  30  that both the battery pack  40  and the AC adapter are not connected. However, the connection node P changes to high level when the AC adapter is connected, which is detected by the micro-controller  30  of such a connection; and the connection node P changes to a low level when the battery pack  40  is connected, but not the AC adapter, which is detected by the micro-controller  30 . 
     FIG. 3A illustrates a detailed schematic of the battery pack  40  having the micro-controller  30  coupled to an EEPROM, the current counter  1 , the battery  2 , and the resistors R 1  and R 2  for coupling to the connection node P. FIG. 3B illustrates the details of the micro-controller  30 , which includes a controller  31  coupled to receive a voltage or P value of the connection node P and the output of the current counter  1 . The micro-controller  30  further includes a remaining capacity register (RM)  32 , the full charge capacity register (FCC)  33  and the discharge count register (DCR)  34 . Moreover, the micro-controller includes a system leakage current timer  35  and a self-discharge timer  36 . 
     The full charge capacity register  33  stores a value corresponding to a full capacity of the battery, which is obtained from the EEPROM. When the battery  2  is fully charged, value stored in the RM  32  equals the value stored in the FCC  33 , and a value of 0 is stored in the DCR  34 . 
     When the battery is discharging by use of the system with the battery  2  and without coupling to an external power source, the value stored in the RM decrements while the value stored in the DCR  34  increments, i.e., the value stored in the RM decreases from a first prescribed value to 0 and the value stored in the DCR  34  increases from 0 to a second prescribed value. 
     In other words, when the battery is charged, value of the remaining capacity register RM  32  increases in proportion to charge of the battery  2 . However, when the battery is discharged, the discharge register counter DCR  34  counts from 0 to + direction, and the value of the remaining capacity register RM  32  decreases. 
     The system leakage (SL) current timer  35  generates a value reflective of the leakage current of the system when the system is turned off. Further, the self-discharge (SD) timer  36  generate a value reflective of the self-discharge when the system is using the battery as the power source without an external power source or when the battery pack is not connected. Such values from the SL current timer  35  and the SD timer  36  are used by the controller to decrease the value stored in the RM  32  and increase the value stored in the DCR  34 . 
     FIGS. 4A and 4B illustrate the method for compensating or accounting for the self-discharge and the leakage current. First, the micro-controller  30  detects a change in value of the current counter  1  of FIG. 3A (S 1 ). If there is a discharge (−), e.g., the system is using the battery for power, the SD timer  36  is started to reflect the self-discharge of battery (S 2 ). However, when the system is connected to an external power source via the AC adapter, the battery is being charged (+), the SL timer  35  and the SD timer  36  are off or remain off (S 3 ). 
     When there is no change in value of the current counter  1 , the micro-controller  30  checks to determine whether the battery pack  40  is disconnected or not installed in the system  50 - 1  base on the value at the connection node P of FIG. 2A or FIG. 2B (S 4 ). If the battery pack  40  is separated from the system, the SD timer  36  is started to reflect the self-discharge of the battery (S 2 ). However, if the battery pack  40  is connected to the system  50 - 1 , the micro-controller  30  checks to determine if there is leakage current using the detector of FIGS. 2A and 2B (S 5 ). If there is no leakage current, the SD timer  36  is started to reflect the self-discharge of the battery (S 2 ). However, if there is leakage current, both the SL timer  35  and the SD timer  36  are started to reflect the self-discharge of the battery and the leak current (S 6 ). After step S 2  or S 6 , the SL timer  35  and/or SD timer  35  waits for an interrupt to be generated (S 7 ). 
     As shown in FIG. 4B, the controller  31  generates an interrupt of the SL timer  35  and the SD timer  36  based on the change of the P value (S 11 ). Thereafter, if there is an SD timer interrupt (S 11 ), the value of the RM register  32  is compensated or adjusted to reflect the self discharge (S 12 ). If there is an SL timer interrupt (S 13 ), the value of the RM register  32  is compensated or adjusted to reflect the leakage current. Thereafter, the method returns to the start to repeat the process (S 15 ). 
     The present invention has various advantages. For example, the present invention compensates for the self discharge. Further, the present invention compensates for the leakage current. Such compensations allow accurate reflections of the battery status, and allow a user to correct manage the remaining charge of the battery. 
     The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. For example, the present invention is not limited to a notebook computer, but is readily applicable to all systems using a battery as an alternate power source, including cameras, camcorders, audio players, radios, cell phones, etc.

Technology Classification (CPC): 7