JP2010246176A - Charging circuit and method of controlling charge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging circuit using batteries in fully charged states at preset charge completion setting time. <P>SOLUTION: The charging circuit 1 is provided with: a power supply control circuit section 6 for generating an internal voltage by an external power supply 3; a control transistor 9 provided between the power supply control circuit section 6 and the battery 2; a battery capacity measurement section 10 for measuring the remaining capacity of the battery 2; a time setting section 11 for setting charge completion setting time of the battery 2; and a control section 12 for controlling a conduction state of the control transistor 9, based on the remaining capacity of the battery 2 and the charge completion setting time of the battery 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charging circuit and a charging control method.

  Currently, mobile phone devices are required to be small and thin, and to have higher functionality. Mobile phone devices with various features, such as LCD (Liquid Crystal Display) screens becoming larger and illumination-oriented, have been put on the market. With regard to basic functions such as calls and e-mails, some users may make and receive tens of calls a day. In addition, depending on user settings such as keeping the LCD screen displayed, current consumption may increase. When used as described above, the battery is very exhausted, and many users charge the battery every day at night. When charging, connect the AC adapter to the mobile phone device and the charging will be completed in about 2 hours. After charging is complete, power will be supplied from the battery. If there are many incoming mails after that, the battery will be depleted. End up. Although the battery should be full after recharging, there were many cases where it seemed that the battery was depleted when waking up in the morning, even though I thought it was not used much.

  FIG. 7 shows a block diagram of a related charging circuit. The charging circuit includes a charging input (+) terminal 4 to which the AC adapter 32 is connected, a charging input (−) terminal 5, a power input (+) terminal 7 to which the battery 2 is connected, and a power input (−) terminal. 8 is provided. The charging circuit further includes a charging circuit unit 61 that charges the battery 2 by supplying power from the AC adapter 32, a power circuit unit 62 that generates and supplies internal power to be used inside the charging circuit by supplying power from the battery 2, and charging A control unit 12 for monitoring the operation state of the circuit is provided. The control unit 12 includes a CPU (Central Processing Unit) 121 that controls the entire charging circuit, and a ROM (Read Only Memory) 122 in which a control program for causing the CPU 121 to function is recorded. The battery voltage Vb and the system power supply voltage Vs supplied to the power supply circuit unit 62 have the same voltage value.

  In such a charging circuit, charging is started at the same time as the AC adapter 32 is connected as shown in FIG. The battery voltage Vb and the system power supply voltage Vs increase with the lapse of time, and charging is completed in about 2 hours. The battery voltage Vb becomes 4.2V. Thereafter, when an incoming mail is received by the mobile phone device equipped with the charging circuit, the battery voltage Vb decreases because current is consumed by the internal circuit operation through the system power supply voltage Vs. If the time from when the charging is completed until the user starts using the mobile phone device is long, there is a problem that the battery is often exhausted.

  Therefore, the charging circuits of Patent Documents 1 and 2 measure the remaining battery capacity of the electronic device when connected to the AC adapter, calculate the scheduled charging time from the remaining battery capacity, and from the charging completion setting time set by the user The scheduled charge start time is calculated by subtracting the scheduled charge time.

JP 2000-253596 A JP-A-8-214412

  The charging circuits of Patent Documents 1 and 2 simply wait for charging of the battery by a timer or the like. That is, since power is supplied from the battery to the electronic device during standby, the battery is consumed and the battery voltage decreases. Since the battery remaining capacity is measured and the estimated charging start time is derived immediately after the electronic device is connected to the AC adapter, if the battery is depleted thereafter, the charging time of the battery will be prolonged or the charging will be performed accordingly. The battery may not be fully charged at the completion set time.

  An object of the present invention is to provide a charging circuit and a charging control method that solve the above-described problems.

  The charging circuit of the present invention includes a power supply control circuit unit that generates an internal voltage from an external power supply, a control transistor provided between the power supply control circuit unit and the battery, and a battery capacity measurement unit that measures the remaining capacity of the battery And a time setting unit for setting the charging completion setting time of the battery, and a control unit for controlling the conduction state of the control transistor based on the remaining capacity of the battery and the charging completion setting time of the battery. .

  The charging control method of the present invention controls the charging current to the battery based on the remaining capacity of the battery connected to the charging circuit and the charging completion set time of the battery.

  According to the present invention, it is possible to provide a charging circuit and a charging control method capable of using a battery in a fully charged state at a preset charging completion setting time.

It is a block diagram which shows roughly the structure of the charging circuit which concerns on this invention. It is a flowchart figure which shows schematically the charge control method which concerns on this invention. (A) is a figure which shows the relationship between a battery voltage and time in the charging circuit and charge control method of Example 1. FIG. (B) is a figure which shows the relationship between a system power supply voltage and time in the charging circuit and charging control method of Example 1. FIG. (C) is a figure which shows the relationship between a charging control signal and time in the charging circuit and charging control method of Example 1. FIG. It is a figure which shows the relationship between a battery voltage and time in the charging circuit and charge control method of Example 2. It is a figure which shows the relationship between the battery voltage and time in the charging circuit and charge control method of Example 3. It is a figure which shows the relationship between a battery voltage and time in the charging circuit and charge control method of Example 4. It is a block diagram which shows schematically the structure of a related charging circuit. It is a figure which shows the relationship between a battery voltage (system power supply voltage) and time in the related charging circuit and charge control method.

  Embodiments of a charging circuit and a charging control method according to the present invention will be described. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

<Embodiment 1>
As shown in FIG. 1, the charging circuit 1 according to the present embodiment includes a battery 2 connected to an electronic device such as a mobile phone device in order to charge the battery 2 by supplying power from an external power source 3. Installed.

The charging circuit 1 includes charging input terminals 4 and 5, a power supply control circuit unit 6, power supply input terminals 7 and 8, a control transistor 9, a battery capacity measurement unit 10, a time setting unit 11, and a control unit 12.
The charging input terminals 4 and 5 are terminals to which the external power supply 3 is connected. The external power supply 3 includes an AC power supply unit 31 and an AC adapter 32. That is, the external power supply 3 uses the AC power supplied from the AC power supply unit 31 as the DC power by the AC adapter 32. The power supply side of the AC adapter 32 is electrically connected to the charging input (+) terminal 4. The ground power supply side of the AC adapter 32 is electrically connected to the charging input (−) terminal 5.

  The power supply control circuit unit 6 generates an internal voltage from the external power supply 3. The power supply control circuit unit 6 includes a charging circuit unit 61 and a power supply circuit unit 62. The charging circuit unit 61 charges the battery 2 by supplying power from the external power supply 3. The charging circuit unit 61 includes a connection detection unit (not shown) that detects whether or not the external power source 3 is connected to the charging input terminals 4 and 5. The connection detection unit is charged by the external power source 3. Information indicating connection to the input terminals 4 and 5 is output to the control unit 12. The power supply circuit unit 62 generates and supplies internal power to be used inside the charging circuit 1 by supplying power from the battery 2 or the charging circuit unit 61.

  The power input terminals 7 and 8 are terminals to which the battery 2 is connected. The battery 2 is a battery mounted on an electronic device such as a mobile phone device. The positive electrode side of the battery 2 is electrically connected to the power input (+) terminal 7. The negative electrode side of the battery 2 is electrically connected to the power input (−) terminal 8.

  The control transistor 9 is, for example, a p-channel MOS (Metal Oxide Semiconductor) transistor. The control transistor 9 is connected between the charging circuit unit 61 and the power supply input (+) terminal 7. That is, the source of the control transistor 9 is electrically connected to the charging circuit unit 4. The drain of the control transistor 9 is electrically connected to the power supply input (+) terminal 7. The gate of the control transistor 9 is electrically connected to the control unit 12. As will be described in detail later, the control transistor 9 is charged from the charging circuit unit 61 to the battery 2 by a charging control signal Cs from the control unit 12. That is, the control transistor 9 is turned on when the charging control signal Cs from the control unit 12 is at the low level, and the battery 2 is charged from the charging circuit unit 61. The control transistor 9 is turned off when the charging control signal Cs from the control unit 12 is at a high level, and the connection between the charging circuit unit 61 and the battery 2 is disconnected. At this time, the power supply voltage at the same level as the rated voltage of the battery 2 is supplied from the charging circuit unit 61 to the power supply circuit unit 62 as the system power supply voltage Vs.

  The battery capacity measuring unit 10 measures the remaining capacity of the battery 2. The battery capacity measurement unit 10 includes a resistor 101 and a measurement unit 102. One terminal of the resistor 101 is electrically connected to the power supply input (−) terminal 8. The other terminal of the resistor 101 is electrically connected to the ground terminal. The measurement unit 102 is electrically connected to both sides of the resistor 101. Thereby, the measurement unit 102 measures the voltage across the resistor 101 connected to the power input (−) terminal 8 and calculates the current value, thereby measuring the remaining capacity of the battery 2. The measurement unit 102 periodically outputs information indicating the measurement result to the control unit 12.

  The time setting unit 11 sets the charging completion setting time of the battery 2. Specifically, the time setting unit 11 prompts the user to input the charging completion setting time of the battery 2 from the display unit of the mobile phone device, for example, and the charging completion setting time of the battery 2 input using a numeric keypad or the like. Is output to the control unit 12. Incidentally, the time setting unit 11 of the present embodiment includes a timer unit 111. The timer unit 111 operates based on the standby time information from the control unit 12 and outputs the standby time elapsed information to the control unit 12 after the standby time has elapsed.

  The control unit 12 controls the conduction state of the control transistor 9 based on the input remaining capacity of the battery 2 and the charging completion setting time of the battery 2. That is, although the details will be described later, the control unit 12 controls the charging current to the battery 2 so that the charging of the battery 2 is completed at the charging completion set time.

  The control unit 12 includes a CPU (Central Processing Unit) 121 that controls the charging circuit, that is, the entire electronic device, and a ROM (Read Only Memory) 122 that stores a control program for causing the CPU 121 to function. . The control unit 12 includes a real time clock having a clock function, and the current time is stored in the ROM.

The controller 12 operates as shown in FIG. 2 and realizes a charge control method.
That is, when information indicating that the external power supply 3 is connected to the charging input terminals 4 and 5 is input from the charging circuit unit 61, the CPU 121 connects the AC adapter 32 to the charging input terminals 4 and 5 from the ROM 122. The obtained time, that is, the current time is acquired (step S1). The CPU 121 acquires the remaining capacity of the battery 2 that is intermittently input from the ROM 122.

The CPU 121 acquires the charging completion set time from the ROM 122 (step S2).
CPU 121 calculates a scheduled charging time based on the remaining capacity of battery 2 (step S3). Since the charging capacity is determined by “current × time”, the scheduled charging time is calculated by first subtracting the capacity when the battery 2 is fully charged and the remaining capacity, and calculating the capacity of the battery to be charged (charging battery capacity). Then, the scheduled charging time is calculated by dividing the charging battery capacity by the charging current value. As the battery capacity at the time of full charge, the battery capacity stored in the ROM 122 is used.

The CPU 121 compares the time obtained by subtracting the charging completion set time and the time when the AC adapter 32 is connected to the charging input terminals 4 and 5 with the scheduled charging time (step S4).
When the time obtained by subtracting the charging completion set time and the time when the AC adapter 32 is connected to the charging input terminals 4 and 5 is longer than the scheduled charging time, the CPU 121 connects the external power source to the charging completion setting time and the charging circuit. The standby time is calculated by subtracting the scheduled charging time from the time obtained by subtracting the time (step S5).
The CPU 121 outputs standby time information to the timer unit 111 of the time setting unit 11 (step S6).

  At this time, the charging circuit 1 is in a standby state for charging the battery 2. The control unit 12 controls the conduction state of the control transistor 9 so that the connection between the charging circuit unit 61 and the battery 2 is disconnected until the standby time elapses. That is, when the battery 2 is in a standby state for charging, the control unit 12 inputs a high-level charge control signal Cs to the gate of the control transistor 9. As a result, the connection between the battery 2 and the charging circuit unit 61 is disconnected. On the other hand, the external power supply 3 and the charging circuit unit 61 are maintained in a connected state. Therefore, as described above, the power supply voltage at the same level as the rated voltage of the battery 2 is supplied from the charging circuit unit 61 to the power supply circuit unit 62 as the system power supply voltage Vs, and the electronic device operates at the system power supply voltage Vs. become. Therefore, in the charging circuit and the charging control method, when the battery 2 is in a standby state, the battery 2 is not consumed and the battery voltage does not decrease. The charging completion time is not significantly shifted from the time, and charging of the battery 2 is not completed. Therefore, the battery 2 can be used in a fully charged state at a preset charge completion set time.

After the standby time of the battery 2 elapses, standby time elapsed information is input to the CPU 121 from the timer unit 111 (step S7).
When the standby time elapsed information is input, the CPU 121 generates a low-level charge control signal Cs to be applied to the gate of the control transistor 9 in order to connect the charging circuit unit 61 and the battery 2. (Step S8).

  On the other hand, if the time obtained by subtracting the charging completion set time and the time when the AC adapter 32 is connected to the charging input terminals 4 and 5 is shorter than the scheduled charging time, the CPU 121 controls the battery 2 to start charging immediately. A low level charge control signal Cs to be supplied to the gate of the transistor 9 is generated and output to the gate of the control transistor 9. That is, the CPU 121 proceeds from step S4 to step S8.

  When the external power source 3 is removed from the charging input terminals 4 and 5, the connection detection unit of the charging circuit unit 61 displays information indicating that the external power source 3 has been removed from the charging input terminals 4 and 5. Output to a switching unit (not shown). Then, the back gate switching unit switches the source and drain of the control transistor 9 in reverse. Thereby, the charging circuit 1 is driven by power supply from the battery 2 as an internal circuit of the electronic device.

  In the above embodiment, the timer unit 111 included in the time setting unit 11 measures the standby time and determines whether or not the charging start time has come, but this is not the case. That is, the CPU 121 of the control unit 12 calculates the scheduled charging start time by subtracting the scheduled charging time from the charging completion set time. Then, the CPU 121 determines whether or not the scheduled charging start time is reached based on the current time acquired from the ROM 122. When the scheduled charging start time is reached, the conduction state of the control transistor 9 is started to start charging the battery 2. To control. Also in this case, the CPU 121 of the control unit 12 controls the conduction state of the control transistor 9 so as to disconnect the connection between the charging circuit unit 61 and the battery 2 until the scheduled charging start time.

  In the above embodiment, the control unit 12 controls the conduction state of the control transistor 9 so that the charging of the battery 2 is completed just at the charging completion set time. The control unit 12 may control the conduction state of the control transistor 9 so that the charging of the battery 2 is completed with a margin with respect to the charging completion set time.

  In the above embodiment, the user sets the charging completion set time using the numeric keypad or the like, but this is not restrictive. When the electronic device on which the charging circuit of the present invention is mounted is, for example, a mobile phone device or the like, the set time for the alarm function or the like is stored in the ROM 122 of the control unit 12 in advance. It may be used as the completion set time.

In the above embodiment, a p-channel MOS transistor is used as the control transistor 9, but an n-channel MOS transistor can be used in substantially the same manner.
In the above embodiment, the resistor 101 is inserted on the negative electrode side of the battery 2, but may be inserted on the positive electrode side.

  The present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

<Example 1>
In this embodiment, an example in which the remaining capacity of the battery 2 is small is shown.
As shown in FIG. 3, when the external power supply 3 is connected at time (0:00), the control unit 12 calculates the scheduled charging time (2 hours) from the remaining battery capacity. The control unit 12 determines that the standby time is set to 4 hours because the 6 hours from the connection time (0:00) of the external power supply 3 to the charging completion set time (6:00) is longer than the scheduled charging time (2 hours). The standby time information is output to the timer unit 111. The timer unit 111 starts when the standby time information is input, and outputs the standby time elapsed information to the control unit 12 after 4 hours. When the standby time elapsed information is input, the control unit 12 controls the conduction state of the control transistor 9 to start charging the battery 2. After 2 hours, the battery 2 is fully charged. In this case, the battery voltage Vb is charged from 3.2V, and becomes 4.2V when charging is completed. In the charging standby time, the charging control signal Cs is at a high level, the control transistor 9 is turned off, and the system power supply voltage Vs is supplied with a constant voltage (4.2 V) from the charging circuit unit 61. After the charging standby time elapses, the charging control signal Cs becomes low level, the control transistor 9 is turned on, and the system power supply voltage Vs is supplied with the battery voltage Vb.

<Example 2>
In this embodiment, an example in which the remaining capacity of the battery 2 is large is shown. The battery voltage Vb is charged from 3.7V.
As shown in FIG. 4, when the external power supply 3 is connected at time (0:00), the control unit 12 calculates a scheduled charging time (1.5 hours) from the remaining battery capacity. The control unit 12 determines that the charging standby time is 6 hours from the connection time (0:00) of the external power supply 3 to the charging completion set time (6:00) is longer than the scheduled charging time (1.5 hours). It calculates 4.5 hours and outputs the waiting time information to the timer unit 111. The timer unit 111 starts when the standby time information is input, and outputs the standby time elapsed information to the control unit 12 after 4.5 hours. When the standby time elapsed information is input, the control unit 12 controls the conduction state of the control transistor 9 to start charging the battery 2. After 1.5 hours, the battery 2 is fully charged. The charging start time is 30 minutes later than that in FIG.

<Example 3>
In the present embodiment, an example is shown in which the time obtained by subtracting the charging completion set time and the time when the AC adapter 32 is connected to the charging input terminals 4 and 5 is equal to the scheduled charging time.
As shown in FIG. 5, when the external power supply 3 is connected at time (0:00), the control unit 12 calculates the scheduled charging time (2 hours) from the remaining battery capacity. Then, the control unit 12 determines that the charging standby time is 0 hour because the two hours from the connection time (0:00) of the external power supply 3 to the charging completion set time (2:00) are equal to the scheduled charging time (2 hours). And calculate. Therefore, the control unit 12 does not output the standby time information to the timer unit 111, and immediately controls the conduction state of the control transistor 9 to start charging the battery 2. After 2 hours, the battery 2 is fully charged. Similarly, when the comparison result between the time from the connection time of the external power supply 3 to the charging completion set time and the scheduled charging time becomes a negative value, the charging starts immediately.

<Example 4>
In this embodiment, an example is shown in which the control unit 12 controls the conduction state of the control transistor 9 so that the charging of the battery 2 is completed with a margin with respect to the charging completion set time.
As shown in FIG. 6, when the external power supply 3 is connected at time (0:00), the control unit 12 calculates the scheduled charging time (2 hours) from the remaining battery capacity. The controller 12 then sets the charging completion time to 6: 6 because the 7 hours from the connection time (0:00) of the external power supply 3 to the charging completion setting time (7:00) is longer than the scheduled charging time (2 hours). The charging standby time is calculated as 4 hours, assuming 00. Further, the control unit 12 outputs standby time information to the timer unit 111. The timer unit 111 starts when the standby time information is input, and outputs the standby time elapsed information to the control unit 12 after 4 hours. When the standby time elapsed information is input, the control unit 12 controls the conduction state of the control transistor 9 to start charging the battery 2. After 2 hours, the battery 2 is fully charged.

DESCRIPTION OF SYMBOLS 1 Charging circuit 2 Battery 3 External power supply, 31 Power supply part, 32 AC adapter 4, 5 Input terminal for charging 6 Power supply control circuit part, 61 Charging circuit part, 62 Power supply circuit part 7, 8 Power supply input terminal 9 Control transistor 10 Battery capacity measurement unit, 101 resistance, 102 measurement unit 11 time setting unit, 111 timer unit 12 control unit Cs charge control signal Vb battery voltage Vs system power supply voltage

Claims (14)

A power supply control circuit that generates an internal voltage from an external power supply;
A control transistor provided between the power control circuit unit and the battery;
A battery capacity measuring unit for measuring the remaining capacity of the battery;
A time setting unit for setting the charging completion setting time of the battery;
A control unit for controlling a conduction state of the control transistor based on a remaining capacity of the battery and a charging completion setting time of the battery;
A charging circuit comprising:   When the external power source is connected to the charging circuit, the control unit calculates a scheduled charging time based on the remaining capacity of the battery, and further connects the external power source to the charging completion set time and the charging circuit. When the time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit is longer than the scheduled charging time The standby time is calculated by subtracting the scheduled charging time from the time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit, and the charging of the battery is started after the standby time has elapsed. The charging circuit according to claim 1, wherein the conduction state of the control transistor is controlled.   3. The charging according to claim 2, wherein the control unit controls a conduction state of the control transistor so as to disconnect the power supply control circuit unit from the battery until the standby time elapses. circuit.   When the external power source is connected to the charging circuit, the control unit calculates a scheduled charging time based on the remaining capacity of the battery, and further connects the external power source to the charging completion set time and the charging circuit. When the time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit is longer than the scheduled charging time A scheduled charging start time is calculated by subtracting the scheduled charging time from a charging completion set time, and the conduction state of the control transistor is controlled to start charging the battery at the scheduled charging start time. The charging circuit according to claim 1.   5. The control unit according to claim 4, wherein the control unit controls the conduction state of the control transistor to disconnect the power supply control circuit unit and the battery until the scheduled charging start time is reached. Charging circuit.   When the time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit is shorter than the scheduled charging time, the control unit conducts the control transistor to start charging the battery. The charging circuit according to claim 1, wherein the state is controlled.   The charging circuit according to claim 1, wherein the control transistor is a p-channel MOS transistor.   The charging circuit according to claim 1, wherein the control transistor is an n-channel MOS transistor.   A charging control method for controlling a charging current to the battery based on a remaining capacity of the battery connected to a charging circuit and a charging completion setting time of the battery. Based on the remaining capacity of the battery, the estimated charging time is calculated,
Comparing the scheduled charging time with the time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit, the charging completion setting time and the time when the external power source is connected to the charging circuit When the subtracted time is longer than the scheduled charging time, the standby time is calculated by subtracting the scheduled charging time from the time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit,
The charging control method according to claim 9, wherein a charging current to the battery is controlled to start charging the battery after the standby time has elapsed.   The charging control method according to claim 10, wherein an internal voltage is generated by the external power supply until the standby time elapses. Based on the remaining capacity of the battery, the estimated charging time is calculated,
Comparing the scheduled charging time with the time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit, the charging completion setting time and the time when the external power source is connected to the charging circuit When the subtracted time is longer than the scheduled charging time, the scheduled charging start time is calculated by subtracting the scheduled charging time from the charging completion set time,
The charging control method according to claim 9, wherein a charging current to the battery is controlled to start charging the battery at the scheduled charging start time.   13. The charge control method according to claim 12, wherein an internal voltage is generated by the external power supply until the scheduled charging start time is reached.   When a time obtained by subtracting the charging completion set time and the time when the external power source is connected to the charging circuit is shorter than the scheduled charging time, the charging current to the battery is controlled to start charging the battery. The charge control method according to claim 9, wherein:

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