JP2002369374A - Overdischarge preventing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overdischarge preventing circuit for preventing overdischarge of a secondary battery. SOLUTION: An output of a three-terminal regulator 42 is stopped by a transistor Q12. This breaking state is maintained by a transistor Q14. When a microcomputer 41 is operated, a switch 43 is closed, power is supplied to the regulator 42, and power is supplied to the microcomputer 41. Discharge of a battery 23 to the microcomputer 41 is restrained, thereby increasing the discharging time of the battery 23 and preventing the overdischarging of the battery 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an overdischarge prevention circuit for preventing an overdischarge of a secondary battery.

[0002]

2. Description of the Related Art Conventionally, as this kind of overdischarge prevention circuit, for example, a configuration shown in FIG. 12 is known.

In the overdischarge prevention circuit shown in FIG. 12, a charging circuit 2 for rectifying and smoothing an AC voltage from the commercial AC power supply is connected to a plug 1 connected to the commercial AC power supply. The emitter of the switching transistor Q1 is connected to the positive electrode of the charging circuit 2, and the base of the transistor Q1 is connected to the microcomputer 3 as control means.

Further, a secondary battery E is connected to the charging circuit 2 via a transistor Q1.

Further, a diode D1 is connected from the positive electrode of the charging circuit 2 to the diode D1.
Is connected to an input terminal of a three-terminal regulator 4 as a constant voltage means, an output terminal of the three-terminal regulator 4 is connected to the microcomputer 3, and a negative electrode of the three-terminal regulator 4 is connected to a negative electrode of the charging circuit 2. Have been. The microcomputer 3 outputs to a motor or a light emitting diode (not shown).

Further, the positive terminal of the charging circuit 2 is connected to the input terminal of the three-terminal regulator 4 via the emitter and the collector of the transistor Q2, and the OR circuit 5 is constituted by the diode D1 and the transistor Q2.

A series circuit of a resistor R2 and a resistor R3 is connected between the emitter and the base of the transistor Q2. Is connected to the negative electrode.

When the charging circuit 2 is not connected, the Zener diode ZD1 is turned on if the voltage value of the secondary battery E is equal to or higher than a predetermined value. Power is supplied to the three-terminal regulator 4 via the transistor Q2, and the three-terminal regulator 4 outputs a constant voltage to operate the microcomputer 3.

When the charging circuit 2 is connected, power is supplied from the charging circuit 2 to the three-terminal regulator 4 via the diode D1, and the three-terminal regulator 4 outputs a constant voltage to To work. Further, the microcomputer 3 detects the voltage of the secondary battery E, and when the voltage value of the secondary battery E is equal to or less than the predetermined value, the microcomputer 3 turns on the transistor Q1 continuously or in a pulsed manner, and To charge the secondary battery E. On the other hand, when the voltage of the secondary battery E is equal to or higher than the predetermined value, the microcomputer 3 turns off the transistor Q1 and does not charge the secondary battery E. With this configuration, the charging current can be controlled using the microcomputer 3 provided in the device main body.

[0010]

However, in the above conventional example, when the secondary battery E is not charged, the secondary battery E is used regardless of whether the microcomputer 3 is used or not.
Is supplied to the microcomputer 3 from the
The secondary battery E may be overdischarged.

In the state where the battery is connected to the charging circuit 2, the microcomputer 3 supplements the discharged secondary battery E and replenishes the discharged electric charge every day, for example, every 24 hours. It is possible.

However, the charging circuit 2 is manufactured and sold.
Therefore, when the period until charging the secondary battery E is long, there is a problem that the charging circuit 2 is not connected to the secondary battery E and the secondary battery E may be over-discharged. I have.

The present invention has been made in view of the above problems, and has as its object to provide an overdischarge prevention circuit for preventing overdischarge of a secondary battery E.

[0014]

An overdischarge prevention circuit according to a first aspect of the present invention includes a driving unit driven by power from at least one of a secondary battery and a charging circuit for charging the secondary battery, and a secondary battery. And a constant voltage output means for outputting a constant voltage from a power supply from at least one of a charging circuit for charging the secondary battery, and the driving means operating by an output of the constant power output means and operating according to a state set by the operation means. , An interrupting unit for stopping the output of the constant voltage output unit, an interruption maintaining unit for maintaining the interrupted state of the interrupting unit, and an output of the constant voltage output unit stopped by the interrupting unit. And a shut-off maintaining release means for releasing the shut-off maintaining state of the shut-off maintaining means in the state. The output of the constant voltage output means is stopped by the shut-off means, and the shut-off maintaining means is shut off by the shut-off maintaining means. After the voltage is maintained, the output of the constant voltage output unit is stopped until the interruption maintaining state of the interruption maintaining unit is released by the interruption maintaining release unit, and the discharge to the control unit of the secondary battery until power is supplied from the charging circuit is stopped. By suppressing the discharge time of the secondary battery, the secondary battery is prevented from being over-discharged.

According to a second aspect of the present invention, there is provided an overdischarge prevention circuit according to the first aspect, wherein the operation means for setting the control of the driving means and the control means are turned off unless the operation means is operated for a predetermined time or more. The power supply is shut off by the means, and if the operation means is not operated for a predetermined time or more, the power supply is cut off by the cutoff means, so that when the cleaning is considered to be completed, the constant voltage means of the secondary battery is promptly turned off. The discharge of the secondary battery through the control means is suppressed to prolong the discharge time of the secondary battery, thereby preventing the secondary battery from being over-discharged.

According to a third aspect of the present invention, there is provided an overdischarge prevention circuit according to the first or second aspect, further comprising voltage detection means for detecting a voltage of the secondary battery, and wherein the control means controls the voltage of the secondary battery. When the voltage drops below a predetermined value, the power supply is cut off by the cutoff means, and when the voltage detection means determines that the voltage of the secondary battery has dropped below the predetermined value, the power supply is cut off by the cutoff means, After the voltage of the secondary battery drops, the discharge to the control means via the constant voltage means of the secondary battery is promptly suppressed, the discharge time of the secondary battery is lengthened, and the secondary battery becomes overdischarged To prevent that.

According to a fourth aspect of the present invention, there is provided an overdischarge prevention circuit according to any one of the first to third aspects, further comprising a charge detection means for detecting the end of charging of the secondary battery, and the control means includes: When the end of the charging of the secondary battery is detected by the means, the output of the constant voltage output means is stopped by the interrupting means. When the end of charging of the secondary battery is detected, the control means outputs the constant voltage output by the interrupting means. In order to stop the output of the means, after the charging of the secondary battery is completed, immediately suppress the discharge of the secondary battery to the control means via the constant voltage means, to increase the discharge time of the secondary battery, Prevent the secondary battery from being over-discharged.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum cleaner using an embodiment of the overdischarge prevention circuit of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, reference numeral 11 denotes a charging cleaner main body. The cleaning cleaner main body 11 has a case body 12 and a rear part connected to an upper part of the case body 12 to open the upper part by rotation. Body case 14 with a lid 13 that is mounted so as to cover it
have.

Further, a main body suction port 21 is opened forward on the front lower surface of the lid 13 of the main body case 14, and a substantially Y-shaped handle (not shown) is provided on the upper surface of the lid 13 in a plan view. ing.

A dust cup 22 serving as a bottomed cylindrical dust collection cup is detachably attached to the front side of the main body case 14 in the case body 12.
, A battery 23 serving as a secondary battery, an overdischarge prevention circuit 24 for the battery 23, and an electric blower (not shown) driven by the battery 23 are housed therein.

Further, a base end of a flexible hose body 25 is connected to the main body suction port 21 of the cleaner body 11 and is detachably connected thereto. At the end of the hose body 25, a hand operation unit 26 as operation means bent in a substantially rectangular shape is provided. In a portion facing the base end side of the bent portion in the hand operation unit 26, a stop setting button 31, a weak setting button 32, and a strong setting button 33 for setting a driving state of an electric blower or the like are provided in a row. Have been.

A replaceable suction port 35 is attached to the distal end of the manual operation section 26 of the hose 25 via an extension pipe 34 as a telescopic connecting pipe.

Further, the case body 12 can be detachably attached to the battery.
A charging stand 36 for charging 23 is provided, and a charging circuit 37 is housed in the charging stand 36.

In the overdischarge prevention circuit 24 shown in FIG. 1, a charging circuit 37 for rectifying and smoothing an AC voltage from the commercial AC power supply e and having a rated output voltage of 27 V is connected to the commercial AC power supply e. . The charging circuit 37 is connected to an over-discharge prevention circuit 24 built in a charging vacuum cleaner or the like. The over-discharge prevention circuit 24 is connected to a positive electrode of the charging circuit 37 by a switching transistor for controlling charging. The emitter of Q11 is connected, and the base of this transistor Q11 is connected to the resistor R11
Is connected to a microcomputer 41 constituted by an integrated circuit as control means. Also, the charging circuit 37
Is connected to a series circuit of a resistor R12 and a resistor R13, and a connection point of the resistor R12 and the resistor R13 is connected to the microcomputer 41.

Further, a battery 23 having a rated output voltage of 19.2 V is connected to the charging circuit 37 via a transistor Q11. A series circuit of a resistor R14 and a resistor R15 is connected in parallel with the battery 23, and a connection point between the resistor R14 and the resistor R15 is connected to the microcomputer 41. The microcomputer 41 outputs to a motor such as an electric blower (not shown) or a light emitting diode for display, and is input from the manual operation unit 26.

Further, the positive terminal of the charging circuit 37 is connected to the input terminal of a three-terminal regulator 42 as constant voltage output means via the emitter and collector of the transistor Q11 and the emitter and collector of the transistor Q12 as cutoff means. . Further, a switch 43 is connected in parallel with the transistor Q12 as a cut-off maintaining release unit.

A series circuit of a resistor R16 and a resistor R17 is connected between the emitter and the base of the transistor Q12. A connection point of the resistor R16 and the resistor R17 is connected to the resistor R18 and the collector and the emitter of the transistor Q14 as a cut-off maintaining means. Is connected to the negative electrode of the charging circuit 37. Further, the base of the transistor Q14 is connected to the output terminal of the three-terminal regulator 42 via the resistor R19, and a resistor R20 is connected between the base and the emitter of the transistor Q14.

Next, the operation of the above embodiment will be described with reference to FIG.
This will be described with reference to FIG.

First, as shown in FIG. 3, an operation process is performed (step 1), a battery voltage process is performed (step 2), a charging process is performed (step 3), and the process returns to step 1.

The operation process is as shown in FIG.
The microcomputer 41 determines whether the power supply is turned off (step 11). If the power supply is turned off, the microcomputer 41 turns off the motor of the electric blower (step 12), and sets the time X to 0 (step 1).
3).

If it is determined in step 11 that the processing is not the cutting processing, it is determined whether the processing is strong (step 14). If the processing is determined to be strong, the microcomputer 41 performs strong processing on the motor of the electric blower. (Step 15), and proceed to Step 13.

Further, if it is determined in step 14 that the processing is not strong, it is determined whether the processing is weak (step 16). If it is determined that the processing is weak, the microcomputer 41 weakly processes the motor of the electric blower. (Step 17), and proceed to Step 13.

If it is determined in step 16 that the processing is not weak, 1 is added to time X (step 18).
It is determined whether or not two hours have elapsed (step 19),
If not more than 2 hours, return. On the other hand, if it is determined in step 19 that two hours or more have elapsed, the base of the transistor Q14 of the microcomputer 41 is set to L level (step 20), the transistor Q14 is turned off, the transistor Q12 is turned off, and the three terminals The supply of power to the regulator 42 is stopped, the supply of power to the microcomputer 41 is stopped, and the discharge of the battery 23 is suppressed. Therefore, since the discharge of the battery 23 can be suppressed, even if the period of storage in the warehouse from manufacture and shipment to use is long, the time until the voltage of the battery 23 decreases can be extended, To prevent overdischarge of the battery.

Then, in the battery voltage processing, as shown in FIG. 5, it is determined whether or not the voltage of the battery 23 is equal to or higher than a predetermined voltage of 16 V (step 21). Return to step 21 for battery
When it is determined that the voltage at 23 is smaller than 16 V, the base of the transistor Q14 of the microcomputer 41 is set to L level (step 22), the transistor Q14 is turned off, the transistor Q12 is turned off, and the power to the three-terminal regulator 42 is Then, the supply of power to the microcomputer 41 is stopped, and when the voltage of the battery 23 decreases, the discharge of the battery 23 is suppressed to prevent overdischarge.

In the charging process, as shown in FIG. 6, it is determined whether or not the cleaner body 11 is set on the charging stand 36 (step 31).
When the temperature of the battery 23 is high, the time counter S is set to S = 0, the time counter t for charging the battery 23 is set to t = 0, and A indicating that the temperature of the battery 23 is high is set to A = 0 (step 32). ), Return.

When it is determined in step 31 that the cleaner main body 11 is set on the charging stand 36, the electric blower of the cleaner main body 11 is turned off (step 33), and the temperature T of the battery 23 is reduced.
Is greater than or equal to T1 (step 34).
If the temperature T is equal to or lower than T1, it is determined whether the temperature T of the battery 23 is lower than T2 (step 35).
If the temperature T of Step 3 is equal to or higher than T2, A = 1 is set (Step 3).
6), return.

When it is determined in step 35 that the temperature T of the battery 23 is lower than T2, A = 1, that is, the battery 2
It is determined whether or not the temperature T of Step 3 is higher than the temperature T2 (Step 37). If it is determined that the temperature has ever been higher, Step S is performed.
Is set to S = S + 1, and the time during which the temperature is lowered is counted (step 38). Then, it is determined whether or not S ≧ d, that is, whether or not d has elapsed since the temperature of the battery 23 has decreased (step 39). On the other hand, if it is determined in step 39 that d or more has elapsed after the temperature of the battery 23 has decreased, A = 0, that is, it indicates that the temperature of the battery 23 was not high (step 40).

If it is determined in step 37 that A = 1 is not satisfied, that is, if the temperature of the battery 23 is not high, the overdischarge prevention circuit 24 is connected to the charging circuit 37. The base current flows, the transistor Q11 is turned on, and the battery 23 is charged. A time counter t indicating this charging time is set to t = t + 1 (step 41), and it is determined whether ΔT ≧ a, that is, whether the temperature rise of the battery 23 is equal to or more than a predetermined value (step 42). It is determined whether t ≧ b, that is, whether the charging time has reached b (step
43) When the value of b has been reached, the microcomputer 41 turns off the transistor Q11 and terminates the charging of the battery 23 (step 44). If the temperature rise of the battery 23 is equal to or higher than the predetermined value in step 42, the charging is terminated in step 44.

If it is determined in step 43 that the charging time of the battery 23 has not reached b, it is determined whether T ≧ T2, that is, whether the temperature T of the battery 23 is lower than T2 (step 45). In this case, the charging is terminated in step 44, and if it is determined in step 45 that the temperature T of the battery 23 is lower than T2, the process returns to continue charging the battery 23.

When the charging of the battery 23 is completed in step 44, the transistor Q1 of the microcomputer 41
The base of 4 is set to the L level (step 46), the transistor Q14 is turned off, the transistor Q12 is turned off, the supply of power to the three-terminal regulator 42 is stopped, and the supply of power to the microcomputer 41 is stopped. Thus, the discharge of the battery 23 is suppressed. Therefore, since the discharge of the battery 23 can be suppressed promptly after the charging of the battery 23 is completed, the time until the voltage of the battery 23 decreases can be prolonged, and
Prevent 23 overdischarge.

On the other hand, when the output of the three-terminal regulator 42 is stopped and the microcomputer 41 is operated, the switch 43 of the cut-off maintaining releasing means is turned on, and the three-terminal regulator 42 outputs the signal to the microcomputer 41. A constant voltage is supplied, a base current is supplied from the three-terminal regulator 42 to the base of the transistor Q14, a base current is supplied to the transistor Q14, the transistor Q14 is turned on, and the transistor Q12 is turned on. The regulator 42 outputs a constant voltage, and the microcomputer 41 is maintained in the ON state.

Next, another embodiment will be described with reference to FIG.

The overdischarge prevention circuit 24 shown in FIG.
In the overdischarge prevention circuit 24 shown in FIG. 1, a switch 51 of the hand operation unit 26 is connected in place of the switch 43 of the cut-off maintenance releasing means. Further, a hand operation unit 26 is connected between the collector of the transistor Q11 and a terminal to which the operation state of the microcomputer 41 is input. The hand operation unit 26 is connected via a resistor R21 to a stop setting button 31. A series circuit of the stop setting switch 52 and the resistor R22 corresponding to the, a series circuit of the weak setting switch 53 and the resistor R23 corresponding to the weak setting button 32, and the strong setting switch 54 and the resistor corresponding to the strong setting button 33 A series circuit of R24 and a resistor R25 are connected in parallel. Switch 5
1 is a button for independent setting or a button for weak setting 32
It may be linked to both the and the high setting button 33.

The basic operation is the same as that of the overdischarge prevention circuit 24 shown in FIG. 1, but the switch 51 is operated by operating the weak setting button 32 or the strong setting button 33 during cleaning. Since the three-terminal regulator 42 is closed, the output can be started by the three-terminal regulator 42 even if the output of the three-terminal regulator 42 is stopped, and the operability is improved.

Another embodiment will be described with reference to FIG.

The overdischarge prevention circuit 24 shown in FIG.
Alternatively, it can be used in place of the overdischarge prevention circuit 24 shown in FIG.

The overdischarge prevention circuit 24 shown in FIG.
In the overdischarge prevention circuit 24 shown in FIG. 7, a diode D11 is connected in place of the switch 43 as the cut-off maintaining release unit, and a zener diode ZD11 functioning as a voltage detection unit is connected in place of the resistor R18.

The basic operation is the same as that of the overdischarge prevention circuit 24 shown in FIG. 1, except that the cleaner base 11 is connected to the charging stand 36, and the overdischarge prevention circuit 24 is connected to the charging circuit 37. Then, power is supplied from the charging circuit 37 to the three-terminal regulator 42 via the diode D11, and the three-terminal regulator 42 outputs a constant voltage to operate the microcomputer 41. That is, the microcomputer 41 is operated by placing the cleaner main body 11 on the charging stand 36 connected to the commercial AC power supply e to output the signal to the three-terminal regulator 42. In the state where the charging circuit 37 is connected, the output voltage of the charging circuit 37 is higher than the voltage of the battery 23, so that the power is supplied from the charging circuit 37 to the three-terminal regulator 42 via the diode D11, 42
Output the constant voltage to operate the microcomputer 41.

When the charging circuit 37 is electrically opened and the voltage of the battery 23 is equal to or higher than a predetermined value, the Zener diode ZD11 is at the Zener voltage. Is turned on to supply power from the battery 23 to the three-terminal regulator 42 via the transistor Q12, and the three-terminal regulator 42 outputs a constant voltage to operate the microcomputer 41.

On the other hand, when the voltage of the battery 23 becomes equal to or less than the predetermined value, the Zener diode ZD11 becomes equal to or less than the Zener voltage, so that the transistor Q12 is turned off and the supply of power from the battery 23 to the three-terminal regulator 42 is stopped. Battery 23
To prevent overdischarge of the battery. In this case, since the output of the three-terminal regulator 42 stops, the transistor Q14 is turned off. Therefore, until the next charging circuit 37 is connected, the transistor Q14 is turned off, and no current flows from the battery 23 to the three-terminal regulator 42, and the discharging of the battery 23 can be suppressed. Even if the battery 23 is not charged, the time until the voltage of the battery 23 decreases until the charging circuit 37 is connected can be lengthened and the overdischarge of the battery 23 is prevented.

Further, another embodiment will be described with reference to FIG.

The overdischarge prevention circuit 24 shown in FIG.
In the overdischarge prevention circuit 24 shown in FIG.
And a switch 55 for increasing output is provided in place of the switch 54 for setting strong.

In this case, the basic operation is the same as that of the overdischarge prevention circuit 24 shown in FIG. 7, but operates according to the flowchart shown in FIG. 10 instead of the flowchart shown in FIG.

First, as shown in FIG. 10, the output is started by the three-terminal regulator 42 by operating either the output reduction switch 55 or the output increase switch 56, and the electric blower is driven by medium processing (FIG. 10). Step 5
1) Perform operation processing (step 52), then perform battery voltage processing (step 53), and perform charging processing (step 5).
4) Return to step.

In the operation process, as shown in FIG. 11, instead of the flowchart shown in FIG. 4, it is determined whether or not the power is off (step 61). If it is determined that the power is off, the output of the three-terminal regulator 42 is output. The microcomputer 41 is stopped and power is not supplied to the microcomputer 41 (step 62), and the time X is set to 0 (step 63).

If it is determined in step 61 that the processing is not the disconnection processing, it is determined whether the output is increased (step 64).
If it is determined that the power is high, the microcomputer 41 performs processing to increase the output of the motor of the electric blower (step 6).
5) Go to step 63.

Further, if it is determined in step 64 that the output is not the output increasing process, it is determined whether the output is reduced (step 66).
41 performs processing to reduce the output of the motor of the electric blower (step 67), and proceeds to step 63.

On the other hand, if it is determined in step 66 that the process is not the output reduction process, a process of time X = X + 1 is performed (step 68), and the routine returns.

As described above, in the case of the OFF setting, the output of the three-terminal regulator 42 is reduced to stop the supply of power to the microcomputer 41, and when the output is set to increase or decrease, the electric blower is driven. Only the three-terminal regulator 42 is output to supply power to the microcomputer 41, so that power is supplied to the microcomputer 41 at the minimum necessary for cleaning, and the discharge of the battery 23 can be minimized, The discharging time by one charge of the battery 23 can be lengthened.

The charging vacuum cleaner can be applied to any of a canister type, an upright type and a handy type.

If the circuit current consumption during standby of the microcomputer 41 and the like is 10 mA, the power consumption is 240 mAh in a standby time of 24 hours a day.

On the other hand, when the capacity of the battery 23 is 2400 mAh
Assuming that the current consumption when driving the electric blower is 7.2 A, the electric blower can be normally driven for 20 minutes while the battery 23 is fully charged, but the microcomputer 41 is merely kept on standby for one day. As a result, 1/10 of the capacity of the battery 23 is consumed and the driving time is shortened. However, by not supplying power to the microcomputer 41 or the like during the standby time, the capacity of the battery 23 is suppressed to about the self-discharge. Therefore, it is possible to prevent the driving time from being shortened without performing supplementary charging.

[0064]

According to the overdischarge prevention circuit of the first aspect, after the output of the constant voltage output means is stopped by the cutoff means and the cutoff is maintained by the cutoff maintenance means, the cutoff maintenance means is cut off by the cutoff maintenance release means. Stop the output of the constant voltage output means until the maintenance state is released, suppress the discharge to the control means of the secondary battery until power is supplied from the charging circuit, to increase the discharge time of the secondary battery, The secondary battery can be prevented from being over-discharged.

According to the overdischarge prevention circuit of the second aspect,
In addition to the overdischarge prevention circuit according to claim 1, when the operation means has not been operated for a predetermined time or more, the power supply is cut off by the cutoff means, and the constant voltage of the secondary battery is promptly determined when cleaning is considered to be completed. By suppressing discharge to the control means via the means, the discharge time of the secondary battery can be prolonged, and overdischarge of the secondary battery can be prevented.

According to the overdischarge prevention circuit of the third aspect,
In addition to the over-discharge prevention circuit according to claim 1 or 2, when the voltage detecting means determines that the voltage of the secondary battery has dropped below a predetermined value, the power supply is cut off by the cut-off means.
After the voltage of the secondary battery drops, the discharge to the control means via the constant voltage means of the secondary battery is promptly suppressed, the discharge time of the secondary battery is lengthened, and the secondary battery becomes overdischarged Can be prevented.

According to the overdischarge prevention circuit of the fourth aspect,
In addition to the overdischarge prevention circuit according to any one of claims 1 to 3, when the completion of charging of the secondary battery is detected, the control means stops the output of the constant voltage output means by the cutoff means, so that the charging of the secondary battery is performed. Is completed, the discharge of the secondary battery to the control means via the constant voltage means is promptly suppressed, the discharge time of the secondary battery is lengthened, and the secondary battery can be prevented from being over-discharged.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an overdischarge circuit of a vacuum cleaner showing one embodiment of an overdischarge prevention circuit of the present invention.

FIG. 2 is a perspective view showing an external appearance of the electric vacuum cleaner.

FIG. 3 is a flowchart showing an overall operation of the above.

FIG. 4 is a flowchart showing the same operation process.

FIG. 5 is a flowchart showing a battery voltage process according to the first embodiment.

FIG. 6 is a flowchart showing a charging process according to the first embodiment;

FIG. 7 is a circuit diagram showing an overdischarge prevention circuit according to another embodiment of the present invention;

FIG. 8 is a circuit diagram showing an overdischarge prevention circuit according to another embodiment of the present invention;

FIG. 9 is a circuit diagram showing an overdischarge prevention circuit according to still another embodiment of the present invention.

FIG. 10 is a flowchart showing an overall operation of the embodiment.

FIG. 11 is a flowchart showing the above operation process.

FIG. 12 is a circuit diagram showing a conventional overdischarge prevention circuit.

[Explanation of symbols]

 23 Battery as a secondary battery 37 Charging circuit 41 Microcomputer as control means 42 Three-terminal regulator as constant voltage output means 43, 51 Switch D11 as cut-off maintenance release means Diode Q12 as cut-off maintenance release means Q12 as cut-off means Transistor Q14 Transistor as means to maintain shut-off

Claims (4)

[Claims] A driving means driven by a power supply from at least one of a secondary battery and a charging circuit for charging the secondary battery, and a driving means for driving the secondary battery and at least one of a charging circuit for charging the secondary battery. A constant voltage output unit that outputs a constant voltage from a power supply; a control unit that operates by an output of the constant power output unit and controls the driving unit in accordance with a state set by the operation unit; and an output of the constant voltage output unit. Shut-off means for stopping; shut-off maintaining means for maintaining the shut-off state of the shut-off means; shut-off maintenance for releasing the shut-off maintaining state of the shut-off maintaining means while the output of the constant voltage output means is stopped by the shut-off means. An overdischarge prevention circuit comprising: a release unit. 2. An over-discharge prevention method according to claim 1, wherein said operation means for setting control of said driving means, and said control means interrupts power supply by said interruption means unless said operation means is operated for a predetermined time or more. circuit. 3. The power supply system according to claim 2, further comprising voltage detecting means for detecting a voltage of the secondary battery, wherein the control means shuts off the power supply by the shutoff means when the voltage of the secondary battery falls below a predetermined value. 3. The overdischarge prevention circuit according to 1 or 2. 4. A charge detecting means for detecting the end of charging of the secondary battery, wherein the control means, when the end of charging of the secondary battery is detected by the charging detecting means, the output of the constant voltage output means by the shutoff means. 4. The over-discharge prevention circuit according to claim 1, wherein the circuit is stopped.