JPH07194017A - Charger - Google Patents

Abstract

PURPOSE:To suppress the deterioration of a battery and reduce its charging time by a method wherein, when an ambient temperature detected by a detecting means at a certain time is not higher than a predetermined value, the battery is so controlled as to be discharged first and then charged. CONSTITUTION:VCC which is a power supply voltage is supplied by a regulator 13 and raised and, if it exceeds 2.5V, the voltage is supplied to a backup power supply as the backup power supply voltage VBB through a second diode 30. At that time, a charger 1 is put into a charge waiting state and so set as to start from the discharge first when an ambient temperature detected by a time thermistor 27 is lower than a prescribed value. The discharge is continued with a discharge current of 700 mA which is the rated current of the battery for 1 hour until the terminal voltage drops to 4V. If it is confirmed that the terminal voltage is not higher than 4V, a one-chip microcomputer turns off a 5th transistor 20 to discontinue discharging and turns off a 4th transistor 16 and turns on a 1st transistor 10 to start charging. With this constitution, the deterioration of the battery can be suppressed and a charging time can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charger for a rechargeable secondary battery used in portable electronic equipment and the like.

[0002]

2. Description of the Related Art Although a commonly used charger does not have a discharging function, a charger having a discharging function has been used conventionally.

Conventionally used -Δ with discharge function
7 and 8 show an example of the configuration of the V-type charger. The structure of a conventional battery pack is shown in FIG.

FIG. 7 is an external perspective view of a charger. In FIG. 7, reference numeral 1 is a charger for a rechargeable secondary battery used in a portable electronic device, which is a rectangular box-shaped charger body 1.
a. On one end surface of the charger main body 1a, an AC plug 2 for inserting into a household AC outlet is provided with a cord 2a.
Connected through. Further, on the upper surface of the charger main body 1a, there are provided a first LED 3 for indicating that charging is being performed and a state where charging is completed, and a second LED 4 for indicating that it is in a discharging state. .
Further, a DC terminal 6 is provided in the battery housing portion 5 of the charger body 1a.

FIG. 8 is a circuit configuration diagram of the charger 1 shown in FIG. 7. In FIG. 8, 7 is a transformer for extracting a secondary voltage from an AC power source into which an AC plug 2 is inserted, and 8 is a transformer for extracting the secondary voltage. The diode bridge for rectification for converting the secondary voltage of the generated alternating current into the direct current voltage, 9 is a constant for controlling the current rectified by the diode bridge 8 according to the output load so as to be a constant current. This is a current circuit, and a current of 800 mA flows in the range of 4V to 8V which is the voltage of the battery pack 22 shown in FIG. Reference numeral 10 is a first transistor for turning on / off charging, and 11 is a diode for preventing backflow from the battery pack 22 shown in FIG.
Reference numeral 12 is a second transistor for driving the first transistor 10.

Reference numeral 13 denotes a three-terminal type constant voltage output regulator (REG), which supplies VCC = 5V which is a power source of a control system of the charger main body 1a. Reference numeral 14 is a one-chip microcomputer that is a microprocessor that controls the entire charger 1, and has functions such as a ROM, a RAM, a timer, an interrupt controller, an AD converter, and an IO port. Reference numeral 15 is a third transistor for driving the first LED 3, 16 is a fourth transistor for driving the second LED 4, and 17 is a reset IC for creating a hardware reset, which is an operating voltage of 4.5.
Hardware reset is released when V is exceeded, 18
Is an amplifier for converting the voltage level of the battery into an input level of an AD converter (not shown) of the one-chip microcomputer 14 in order to detect -ΔV; 19 is a discharge circuit for discharging the battery pack 22 of FIG. 9; Is
Fifth for selectively switching between a discharging state and a charging state
The transistor 21 is a sixth transistor for driving the fifth transistor 20.

FIG. 9 is a circuit diagram of a battery pack. In the figure, 22 is a battery pack, the rated voltage of which is 6 V and the rated current of which is 700 mAh. Reference numeral 23 is a rechargeable secondary battery, and 24 is a DC for charging / discharging connected to a portable electronic device (not shown).
The terminal 25 is an automatic reset type breaker which is activated by a temperature or current exceeding a predetermined set value.

In the above structure, the AC outlet has an AC
When the plug 2 is inserted, the AC power is supplied to the transformer 7. The transformer 7 steps down the AC voltage and supplies it to the diode bridge 8. The diode bridge 8 full-wave rectifies the AC voltage supplied from the transformer 7 to convert it into a DC voltage, and supplies the DC voltage to the constant current circuit 9 and the regulator 13. When the power supply VCC is supplied by the regulator 13, the VCC rises, and when the value exceeds the operating voltage of 4.5 V, the reset IC 17 releases the hardware reset, and the one-chip microcomputer 14
Becomes active.

The one-chip microcomputer 14 turns on the second transistor 12 for driving to detect whether or not the battery pack 22 of FIG. 9 is connected. When the second transistor 12 is turned on, the first transistor 10 is turned on and supplies a current to the DC terminal 6 via the diode 11. As the terminal voltage of the DC terminal 6, when the battery pack 22 of FIG. 10 is connected, the voltage of the battery is output, and when it is not connected, the release voltage of 16 V is output.

The battery pack 22 shown in FIG.
Is not connected, the release voltage level-converted by the amplifier 18 is input to an AD converter (not shown) of the one-chip microcomputer 14 to wait for battery connection. Next, the battery pack 2 of FIG.
When 2 is connected, a charging current flows and the current is limited by the constant current circuit 9, so that the terminal voltage drops and a battery voltage lower than the release voltage is output. Terminal voltage is 4V
In the above case, the one-chip microcomputer 14 turns off the first transistor 10 to discharge, temporarily stops the charging current, turns on the fifth transistor 20 for discharging, and simultaneously turns on the fourth transistor 16. Second L
ED4 is turned on to indicate that discharging is in progress.

Discharging is performed in the discharging circuit 19, and the terminal voltage is maintained up to 4 V at 700 mA, which is the rated current per hour of the battery. The detection of 4 V of the terminal voltage is performed by the AD converter of the one-chip microcomputer 14. When confirming that the terminal voltage has become 4 V or less, the one-chip microcomputer 14 turns off the fifth transistor 20 to stop the discharge in order to charge the fourth
The transistor 16 is turned off, the second LED 4 indicating the discharging state is turned off, the first transistor 10 for charging is turned on, and at the same time, the third transistor 15 is turned on and the first LED 3 is turned on for charging. Display that it is in the middle.

The one-chip microcomputer 14 sets A at regular intervals.
The input from the D converter is sampled to detect -ΔV. For detection of −ΔV, the maximum value of the values sampled from the input from the AD converter is stored, and the value obtained by subtracting the value of the next sampling from the stored value is 10
It is judged by the fact that it becomes 0 mV or more. When −ΔV, which is a full charge, is detected, the one-chip microcomputer 14 turns off the first transistor 10 to end the charge, and at the same time turns off the third transistor 15 to turn off the first LED 3 to charge the user. Display that it has finished.

[0013]

However, in a conventional charger having no discharge function, a battery used in a heavy load electronic device or a battery used in a low temperature environment may cause a memory effect depending on various conditions. There is a problem that the discharge capacity of the battery, which cannot obtain a sufficient discharge capacity, cannot be recovered. Further, in the charger having the discharging function as in the above-mentioned conventional example, since the battery is always discharged before being charged at the time of charging, deterioration of the battery is accelerated, and the charging time becomes long because discharging is performed every time. There was a point.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a charger which can suppress deterioration of a battery and shorten the charging time.

[0015]

In order to achieve the above object, the present invention provides a charger having a discharging function, a time measuring means for measuring the time, a detecting means for detecting the ambient temperature, and a means for detecting the ambient temperature. The present invention is characterized by further comprising control means for detecting the ambient temperature by the detection means and controlling the discharge to be performed after the discharge when the detected value becomes equal to or less than a predetermined set value.

Further, in order to achieve the same purpose, it is desirable to include setting means for setting the time at which the detecting means detects the ambient temperature.

[0017]

The ambient temperature is detected at a predetermined time, and when the detected value becomes equal to or lower than the predetermined set value, discharging is performed and then charging is performed.

[0018]

Embodiments of the present invention will be described below with reference to FIGS.

[First Embodiment] First, a first embodiment of the present invention will be described with reference to FIGS. The present embodiment is applied to a commonly used -ΔV type charger.

FIG. 1 is an external perspective view of a charger according to the first embodiment of the present invention, and FIG. 2 is a circuit configuration diagram of the charger of FIG. In addition, in FIG. 1 and FIG. 2, the conventional FIG.
The same parts as those in FIG. 9 are designated by the same reference numerals. Further, the battery pack in the present embodiment has the same configuration as that of the above-described conventional FIG.

1 is different from FIG. 8 in that a 5-bit dip switch (setting means) 26 for setting the time for detecting the ambient temperature is provided in the configuration of FIG.

2 is different from FIG. 9 in that the DIP switch 26, the thermistor (detection means) 27 for detecting the ambient temperature, the resistor 28, and the real-time clock (timekeeping means) for backing up the configuration of FIG. 9 are used. The lithium battery 29 and the second and third diodes 30 and 31 are added.

Each of the 5 bits of the DIP switch 26 is a resistor and is pulled up to VBB which is a backup power supply, and the ON / OFF state of each is confirmed to the IO port of the one-chip microcomputer (control means) 14. Connected as you can. The thermistor 27 measures the ambient temperature by analog-to-digital conversion of the divided voltage of the resistor 28 in a channel different from the -ΔV detection of the AD converter (not shown) in the one-chip microcomputer 14.

The real-time clock measures the date and time, and is provided in the one-chip microcomputer 14. The backup lithium battery 29 is the third
VBB that is a backup power supply via the diode 31
It is connected to the. The second diode 30 is the main charger 1
Backup power supply VB
A voltage for operation is supplied to B.

The reset IC 17 in this embodiment releases the hardware reset when the backup power supply VBB exceeds the operating voltage of 2.5V.

In the above configuration, when the lithium battery 29 is connected, the backup power supply VBB rises via the third diode 31, and when the value exceeds the operating voltage of 2.5 V, the reset IC 17 releases the hardware reset. Then, the one-chip microcomputer 14 is brought into an operating state, and a real-time clock (not shown) inside the one-chip microcomputer 14 starts measuring time and date. The time set by the DIP switch 26 has a weight for each of the 5-bit switches, and when it is ON, "1", "2", "4", "8" from the right of FIG. , And “16”. Therefore, for example, when the two switches from the right in FIG. 2 are turned on at the same time, 1 + 2 = 3 is set, and the setting is made to measure the temperature at 3 o'clock. When all the switches of 5 bits are OFF, the discharge is not performed, and when the switches of all 5 bits are ON, the discharge is performed every time. Further, when the time measured by the real-time clock (not shown) inside the one-chip microcomputer 14 reaches the time set by the DIP switch 26, the AD converter (not shown) of the one-chip microcomputer 14 causes the thermistor 27 to measure ambient temperature data (detected value). ) Is read and compared with a predetermined set value. Then, if the read measurement data is larger than the predetermined set value, the flag is turned on, and if it is smaller, the flag is turned off.

Next, when the AC plug 2 is inserted into the AC outlet, the AC power is supplied to the transformer 7, and the transformer 7 steps down the AC voltage and supplies it to the diode bridge 8. The diode bridge 8 full-wave rectifies the AC voltage supplied from the transformer 7 to convert it into a DC voltage, and supplies the DC voltage to the constant current circuit 9 and the regulator 13. When the power source VCC is supplied by the regulator 13,
The VCC rises, and when the value exceeds 2.5 V, the second
Power is supplied to the backup power supply VBB via the diode 30, and the charger 1 is in a charging standby state.

The one-chip microcomputer 14 turns on the second transistor 12 for driving to detect whether or not the battery pack 22 of FIG. 10 is connected. When the second transistor 12 is turned on, the first transistor 10 is turned on and supplies a current to the DC terminal 6 via the first diode 11. The terminal voltage of the DC terminal 6 outputs the voltage of the battery when the battery pack 22 of FIG. 10 is connected, and outputs the release voltage of 16 V when not connected.

The battery pack 2 of FIG. 10 is connected to the DC terminal 6.
When 2 is not connected, the release voltage level-converted by the amplifier 18 is input to an AD converter (not shown) of the one-chip microcomputer 14 to enter a battery connection waiting state. Next, when the battery pack 22 of FIG. 10 is connected to the DC terminal 6, a charging current flows and the constant current circuit 9
Limits the current, the terminal voltage drops, and a battery voltage lower than the release voltage is output.

Whether discharge is performed or not is determined by comparing the value of the ambient temperature detected by the thermistor 27 for a preset time by the dip switch 26 with a predetermined set value,
As a result, when the detected ambient temperature value is lower than the predetermined set value, that is, when the flag is ON, the discharge is set to start. If the terminal voltage is 4 V or more when it is determined that discharging is performed, the one-chip microcomputer 14 turns off the first transistor 10 to discharge, temporarily stops the charging current, and then the fifth transistor 20 for discharging. And the fourth transistor 16 is turned on at the same time.
The second LED 4 is turned on to indicate that discharging is in progress.

Discharging is performed in the discharging circuit 19, and the terminal voltage is continued to 4V at 700 mA, which is the rated current per hour of the battery. The detection of the terminal voltage 4V is performed by an AD converter (not shown) of the one-chip microcomputer 14. When confirming that the terminal voltage has become 4 V or less, the one-chip microcomputer 14 turns off the fifth transistor 20 in order to perform charging, stops the discharge, and
Turn off the transistor 16 and display the second discharge
The LED4 is turned off, and the first transistor 10 for charging
At the same time as turning on, the third transistor 15 is turned on and the first LED 3 is turned on to indicate that charging is in progress.

The one-chip microcomputer 14 sets A at regular intervals.
The input from the D converter is sampled to detect −ΔV. For the detection of −ΔV, the maximum value of the values sampled from the input from the AD converter is stored, and the value obtained by subtracting the value of the next sampling from the stored value is 10
It is judged by the fact that it becomes 0 mV or more. When −ΔV, which is a full charge, is detected, the one-chip microcomputer 14 turns off the first transistor 10 and terminates the charge, and at the same time turns off the third transistor 15 to turn off the first LED 3 to charge the user. Display the end.

Next, the control operation of the one-chip microcomputer 14 will be described with reference to the flow charts of FIGS. 3 and 4 together with FIG.

First, in step S301 of FIG. 3, the counters and flags required for the software initial processing are cleared, and the ports such as the OFF of the first LED 3 and the second LED 4 and other devices are initialized. Next, in step S302, the first transistor 10 is turned on to supply the charging current to the DC terminal 6, and the next step S2 is performed.
At 03, it waits for the battery to be connected to the DC terminal 6. When the battery is connected, the next step S304
It is determined whether or not the discharge flag is ON in step S6. If the discharge flag is ON, it is determined that the discharge cycle is in progress, and the flow advances to step S305 for discharging. In this step S305, the charging current is once turned off, and the next step S306
Then, the fifth transistor 20 is turned on for discharging to discharge. Next, in step S307, the second LED 4 that is being discharged is turned on, and in the next step S308, it is determined by the AD converter (not shown) of the one-chip microcomputer 14 whether or not the terminal voltage has dropped to 4 V or less for detecting the end of discharge. To do. Then, when it is determined that the discharge is completed, the process proceeds to step S309 in FIG. 4, the fifth transistor 20 is turned off, and in the next step S310, the second LED 4 is turned off to indicate that the discharge is completed. Then, in step S311, the first transistor 10 is turned on to supply the charging current again, and then the overlap step S3 is performed.
At 312, the first LED 3 is turned on to indicate that charging is in progress.

Next, in step S313, the voltage data input from the AD converter of the one-chip microcomputer 14 for sampling -ΔV is sampled, and in the next step S314, the maximum voltage value (for example, 100 mV).
Memorize In the next step S315, the above step S3
The value stored in step 14 is compared with the value sampled in step S313. If the value is 100 mV or less, in step S319, after waiting for about 1 second of sampling, the process returns to step S313 again to input from the AD converter. To do. In step S315, the value stored in step S314 is compared with the value sampled in step S313, and 10
When the voltage becomes 0 mV or more, it is determined that the charging is completed, and in the next step S316, the first transistor 10 is turned off to stop the supply of the charging current to the DC terminal 6.

Next, the process proceeds to step S317, the second LED 4 indicating that charging is being performed is turned off, and the next step S3
In step 18, wait until the battery is removed, and when the battery is removed, the process returns to step S302 in FIG. 3 to enter the battery connection waiting state.

If the discharge flag is not ON in step S304 of FIG. 3, step S3 of FIG.
To proceed to step 11, the first transistor 1
Turn 0 on.

Next, the control procedure of the interrupt processing that occurs every second by the real-time clock (not shown) of the one-chip microcomputer 14 will be described with reference to the flowchart of FIG. The one-chip microcomputer 14 clocks the date and time by starting a timer for a clock (not shown) during the initial processing and counting up an interrupt every 1 second. When an interrupt occurs, step S5 in FIG.
In 01, the date and time are measured, and the next step S50
In 2 it is judged whether the time matches the time of ambient temperature measurement,
If they do not match, the process directly returns. If they do match, the process proceeds to step S503 to read the value of the ambient temperature from an AD converter (not shown). Then step S504
Then, the ambient temperature value read in step S503 is compared with a predetermined set value, and if the read value is lower than the predetermined set value, the discharge flag is turned on in step S505, and if it is higher, the discharge flag is turned off in step S506. And return.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG.

Since the basic structure of the charger in this embodiment is the same as that in FIGS. 1 and 2 of the above-mentioned first embodiment, both of these drawings will be used for explanation. Further, in the control operation of the one-chip microcomputer 14 in this embodiment, the counters and flags necessary for the processing that is the software initial are cleared, the ports such as the OFF of the first LED 3 and the second LED 4 and other devices are initialized. From the above, the series of processes from the determination by the AD converter (not shown) of the one-chip microcomputer 14 to the determination of whether or not the terminal voltage has become 4 V or less for the detection of the end of discharge is the same as that of FIG. 3 of the first embodiment described above. Therefore, the description will be made by diverting the figure.

The present embodiment is applied to a timer type charger. The control of charging in the present embodiment is performed by a timer (not shown) in the one-chip microcomputer 14, and the charging is controlled to stop in 8 hours. In addition, the constant current circuit 9 has a charging current of 150
It is configured to be mA. FIG. 6 is a flowchart showing the control operation of the one-chip microcomputer 14 in this embodiment. Note that steps S601 to S604 and steps S607 to S609 of FIG. 7 are steps S309 to S609 of FIG. 4 of the above-described first embodiment.
312 and steps S316 to S318, the description thereof will be omitted, and the processing unique to the present embodiment will be described.

In step S604 of FIG. 6, after the second LED 4 is turned on to indicate that charging is in progress, the timer in the one-chip microcomputer 14 is started in the next step S605, and the timer overflows in the next step S606. Is counted for 8 hours. When 8 hours have passed and the battery is fully charged, the next step S6
In step 08, the first transistor 10 is turned off in order to stop the supply of the charging current to the DC terminal 6.

Note that the interrupt processing that occurs every second of the real-time clock in this embodiment is the same as in FIG. 5, so a description thereof will be omitted.

[0044]

As described above in detail, according to the charger of the present invention, the ambient temperature is detected at a predetermined time, and when the detected value becomes equal to or lower than the predetermined set value, the battery is discharged and then charged. As a result, the battery deterioration can be suppressed, and the charging time can be significantly shortened as compared with a conventional charger having a discharging function.

[Brief description of drawings]

FIG. 1 is an external perspective view of a charger according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of the charger according to the embodiment.

FIG. 3 is a flowchart showing a control operation of the one-chip microcomputer in the charger according to the embodiment.

FIG. 4 is a flowchart showing a control operation of the one-chip microcomputer in the charger according to the embodiment.

FIG. 5 is a flowchart showing a control operation of interrupt processing by a real-time clock of the same one-chip microcomputer.

FIG. 6 is a diagram of a charger according to a second embodiment of the present invention.
FIG.

FIG. 7 is an external perspective view of a conventional charger.

FIG. 8 is a circuit configuration diagram of the charger.

FIG. 9 is a circuit configuration diagram of a battery pack used in the same charger.

[Explanation of symbols]

 1 Charger 14 One-chip microcomputer (time measuring means) 26 DIP switch (setting means) 27 Thermistor (detection means)

Claims (2)

[Claims] 1. In a charger having a discharging function, a time measuring means for measuring a time, a detecting means for detecting an ambient temperature, an ambient temperature by the detecting means at a predetermined time, and the detected value is a predetermined value. A charger comprising: a control unit that controls to perform charging after discharging when the value is equal to or less than a set value. 2. The charger according to claim 1, further comprising setting means for setting a time at which the detecting means detects the ambient temperature.