JPH1155867A - Charge controller and controlling method for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overcharge due to continuous charging by comparing a voltage with a previous voltage level every time when it is detected, stopping the charging operation when the detected voltage reaches a first voltage level or when it drops below the previous level and resuming the charging operation when the detected voltage drops below a second voltage level. SOLUTION: The charge control section 31 of a charge controller 30 principally comprises a CPU which compares the voltage being detected periodically at a constant interval with a previous voltage level after starting the charging operation of a battery 22. If the detected voltage exceeds over a previous level, charging operation is stopped when a preset first voltage level is reached or when the previous voltage level is not reached. The charging operation is resumed when the voltage drops from the first level to a second lower level through self-discharge. When a current detected voltage level does not exceed over the previously detected voltage level and it is lower than the second voltage level, a charge error alarm is delivered. According to the arrangement, overcharge due to continuous charging can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the charging of a battery for a power supply backup used in an information processing apparatus such as a facsimile apparatus and a POS (point of sale information) terminal having a memory unit requiring a power supply backup. About.

[0002]

2. Description of the Related Art For example, a facsimile apparatus having an image memory for temporarily storing image data to be transmitted to a destination or image data received from the destination is generally stored in the image memory even when the main power supply is cut off. A battery (secondary battery) for power supply backup is mounted so that data can be retained within a certain period of time. This backup battery is connected to the main power supply via a charging circuit, and is charged by power supply from the main power supply while the main power supply is turned on. Then, when the main power supply is interrupted, the discharge is started by the action of the discharge circuit, and the image memory is backed up.

[0003] In a facsimile apparatus and the like, the main power supply is rarely turned off, so that if a power failure does not occur for a long period of time, the battery will be overcharged. Therefore, conventionally, the voltage of a charged battery is monitored, and when the voltage rises to a first voltage level Vb near full charge, charging is stopped, and then the voltage drops to a second voltage level Va by self-discharge. Then, charging was restarted to prevent overcharging of the battery.

FIG. 6 shows a voltage-time characteristic graph of a battery according to such a charge control method. FIG. 7 shows a voltage-time characteristic graph of the battery due to self-discharge. A in FIG. 6 shows an example of characteristics when the ambient temperature in the environment where the battery is placed is low (for example, around 10 ° C.).
B in the figure shows an example of the characteristics when the ambient temperature is high (for example, around 35 ° C.). 7 shows an example of the characteristics of the battery in the initial state, and FIG.
Shows an example of characteristics in the life state of the battery.

That is, in general, the charge rate of a battery tends to decrease as the ambient temperature increases. When the ambient temperature is low, the voltage rises to the first voltage level Vb due to charging, and charging is repeatedly turned off and on. But,
If the battery is charged in a high state, the voltage is saturated before the first voltage level Vd, and if there is no power failure, the battery may be continuously charged for a long time and may be overcharged. Further, even when the ambient temperature is low, the self-discharge speed increases as the life of the battery approaches, and the cycle of charging off and on tends to be shorter.

[0006]

As described above, the conventional battery charging control method stops charging when the voltage of the battery being charged rises to the first voltage level Vb near full charge, and then causes self-discharge. The voltage is at a second voltage level V
In this case, the charging is restarted when the battery voltage drops to a. Therefore, when the ambient temperature of the battery is high, the voltage of the battery being charged saturates before rising to the first voltage level Vb. There is a possibility that the battery life is shortened due to charging.

Further, even if the battery is no longer charged due to a failure of the charging circuit, it cannot be notified to the user. Furthermore, even when the battery is used in an environment with a low ambient temperature, the battery is frequently charged off and on as the battery nears the end of its life, causing stress, resulting in a faster life.

The present invention has been made in view of such circumstances, and a first object of the present invention is to prevent overcharging by continuous charging even when the battery is used in an environment having a high ambient temperature. It is an object of the present invention to provide a battery charging control method and device that can prevent the battery charging. Another object of the present invention is to provide a battery charge control method and apparatus which can notify a user when charging is not performed normally due to a failure of a charging circuit or the like. Further, a third object is to provide a battery charge control method and apparatus capable of quickly detecting the life of a battery.

[0009]

In order to achieve the first object, a charging control method according to the present invention periodically detects a voltage of a battery when the charging of the battery is started. Further, each time a voltage is detected, it is compared with at least the previous voltage value. If the voltage has increased from the previous time, it is determined whether the current voltage has increased to a preset first voltage level. If the current voltage has increased to the first voltage level, charging is performed. Stop. Also, charging is stopped when the current voltage value has not risen from the previous voltage value. Thereafter, when the voltage of the battery drops due to self-discharge and drops to a second voltage level lower than the first voltage level, charging is restarted. In order to achieve the second object, the voltage value detected this time is compared with the previous voltage value, and if the voltage value has not risen from the previous voltage value, the voltage value detected this time is changed to the second voltage value. It is determined whether or not the voltage is equal to or more than the second voltage level, and when the voltage is lower than the second voltage level, a warning of a charging error is issued.

Further, in order to achieve the third object, after charging is stopped because the voltage value detected this time has risen to the first voltage level or has not risen from the previous voltage value, The time required for the battery voltage to fall to the second voltage level is measured, and when the time is shorter than a preset time, the battery life is notified.

[0011] On the other hand, the charging control device of the present invention comprises:
Voltage detecting means for periodically detecting the voltage of the battery being charged, and comparing the voltage with at least the detected voltage value each time the voltage is detected by the voltage detecting means. Saturation judging means for judging whether the voltage has risen, and full charge judging means for judging whether the voltage value detected this time has risen to a first voltage level set in advance when the saturation judging means judges that it has increased from the previous time. A first charge stopping means for stopping charging of the battery when the full charge determining means determines that the voltage has risen to the first voltage level, and a charge of the battery when the saturation determining means determines that the voltage has not increased from the previous time. After the charging is stopped by the second charge stopping means for stopping and the first or second charge stopping means, the voltage of the battery is lower than the first voltage level by self-discharge. Until the voltage level is obtained and a resume charging resuming means charging and lowered.

In order to achieve the second object,
If the saturation determining means determines that the voltage value has not increased from the previous time, the abnormality determining means determines whether the voltage value detected this time has increased to the second voltage level, and the abnormality determining means has increased the voltage value to the second voltage level. If it is determined that there is no charging error, an error notifying means for notifying a charging error is provided.

Further, in order to achieve the third object, after stopping charging by the first or second charging stopping means, the time required for the battery voltage to fall to the second voltage level is measured. And a life notifying means for notifying the life of the battery when the time measured by the time counting means is shorter than a preset time.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a case will be described in which the present invention is applied to charge control of a battery provided for backing up data in an image memory included in a facsimile apparatus from a power failure.

FIG. 1 is a functional block diagram showing the main configuration of the present embodiment. In FIG. 1, reference numeral 10 denotes a facsimile unit for controlling transmission and reception of a facsimile image. The facsimile unit 10 is provided with an image memory 11 for temporarily storing image data and the like received from a partner station. In the figure, reference numeral 20 denotes a power supply unit for supplying drive power to the facsimile unit 10. The power supply section 20 has a main power supply 21 and a backup battery 22, and the main power supply 21 and the battery 22 are wired and connected by a charging circuit 23, a power failure detection circuit 24, and a discharging circuit 25. .
The charging circuit 23 is a circuit for charging the battery 22 by power supply from the main power supply 21.

The power failure detection circuit 24 is a circuit for detecting a power failure of the main power supply 21. The discharge circuit 25 is a circuit for discharging the battery 22 according to a power failure detection signal from the power failure detection circuit 24.

When the power switch SW is turned on, the main power supply 21 converts the AC power supply E into a DC power supply having a predetermined potential and supplies power to the facsimile unit 10 and each unit of a charge control device 30 described later. The battery 22 supplies a DC power of a predetermined potential to the image memory 11 which requires power backup at the time of a power failure of the main power supply 21, and retains the data in the image memory 11 for a certain period of time. For example, a nickel-metal hydride storage battery is used.

In the figure, reference numeral 30 denotes a charge control device for controlling the state of charge of the battery 22. This charge control device 30
Are a charge control unit 31, a voltage detection unit 32, a charge switching unit 3
3, a storage unit 34, a notification unit 35, a time T timer 36, and a time t timer 37.

The charge control section 31 is mainly composed of a CPU, controls each section based on a preset program, and realizes the following charge control function. That is,
When the charging of the battery 22 is started, the voltage Vx of the battery 22 is periodically detected at a constant interval T, and is compared with at least the previous voltage value Vy every time it is detected. It is determined whether the current voltage value Vx has increased to a preset first voltage level Vb, and whether the current voltage value Vx has increased to the first voltage level Vb or whether the current voltage value Vx has been increased to the previous voltage level. If the voltage does not rise above Vy, the charging is stopped. After the charging is stopped, when the voltage Vx of the battery 22 falls to a second voltage level Va lower than the first voltage level Vb by self-discharge, the charging is restarted.
Further, the voltage value Vx detected this time is the voltage value V detected last time.
If it does not rise above y, the voltage value Vx detected this time
Is determined to be equal to or higher than the second voltage level Va, and if it is lower than the second voltage level Va, a warning of a charging error is issued. Further, after the charging is stopped, a time t required for the voltage Vx of the battery 22 to fall to the second voltage level Va is measured, and the time t is set to a predetermined self-discharge life time t
If it is shorter than 1, the life of the battery 22 is notified.

The voltage detecting section 32 detects a voltage Vx corresponding to the charged amount of the battery 22. The charge switching unit 33 switches charging on and off of the charging circuit 23 according to a control command from the charging control unit 31.

The storage unit 34 stores an EPROM (Erasable Pro
grammable Read Only Memoly) and RAM (Random Acc
ess Memoly) and rewritably stores various data necessary for the charge control function of the present invention.
Incidentally, the first voltage level Vb and the second voltage level Va are stored in the EPROM area as shown in FIG.
And the self-discharge life time value t1 are stored. Also, in the RAM area, as shown in FIG.
x, an area m2 for storing the voltage value Vy detected last time, and an area m1 for storing the voltage value Vx detected this time.
and a region m3 of a saturation counter n for counting the number of times not rising above y.

The notification unit 34 issues a warning to the user about a charging error or a battery life. For example, a warning is issued by displaying a message on a display. When a warning is issued by displaying a message on the display, the display on the operation panel of the facsimile unit may be shared.

The time T timer 36 measures a period T for taking in the voltage Vx of the battery 22 detected by the voltage detector 32. The time t timer 37 measures the time t required for the voltage Vx of the battery 22 to decrease to the second voltage level Va by self-discharge.

In the charging control device 30 having such a configuration, when the power is supplied from the main power supply 21 by turning on the power switch SW, the charging control unit 31 controls each unit according to the procedure shown in the flowcharts of FIGS. Thereby, the charge control function described above is realized. The storage unit 3 based on the charging and self-discharge characteristics of the battery 22 to be charged and the specifications of the device using the battery 22 in advance.
The first voltage level Vb, the second voltage level Va and the self-discharge life value t are set in the EPROM area No. 4 in advance. For example, a voltage value corresponding to the time when the battery 22 is fully charged is set as the first voltage level Vb, and the second voltage level Va is set.
A voltage value corresponding to the amount of charge that at least satisfies the specification of the data backup time of the image memory 11 is set as the self-discharge life value t. Second by discharge
時間 of the time required to decrease to the voltage level Vb
To set the time. When the control is started, the charge control unit 31 first detects a voltage Vx corresponding to the current charge amount of the battery 22 via the voltage detection unit 32 as ST (step) 1 and stores the voltage Vx in the RAM area m1 of the storage unit 35. Store. At this time, the charging circuit 23 is off, and the battery 22 is not charged. Next, as ST2, the voltage value Vx stored in the RAM area m1 and E
A comparison is made with a first voltage level Vb preset in the PROM area. As a result, when the voltage value Vx is lower than the first voltage level Vb, the charging circuit 23 is turned on via the charging switching unit 33 as ST3, and the battery 2 is turned on.
2 starts charging. When the voltage value Vx is equal to or higher than the first voltage level Vb, charging is started after the battery voltage becomes lower than the first voltage level Vb due to self-discharge of the battery.

In response to the start of charging of the battery 22, the charging control section 31 initializes a saturation counter n of the RAM area m3 to [0] in ST4. Also, as ST5, RAM
The voltage value Vx of the area m1 is moved to the RAM area m2, and the time counting operation of the time T timer 36 is started. Then, when it is confirmed that the time T has been measured by the time T timer 36 in ST6, the voltage V corresponding to the current charge amount of the battery 22 is again passed through the voltage detector 32 in ST7.
x is detected and stored in the RAM area m1 of the storage unit 35 (voltage detection means).

Next, as ST8, the voltage value Vx stored in the RAM area m1 and the voltage value Vy stored in the RAM area m2
To determine whether the voltage value Vx is higher than the voltage value Vy (saturation determining means). As a result, when the voltage value Vx is higher than the voltage value Vy, the voltage value Vx is compared with the first voltage level Vb in ST9 to determine whether the voltage value Vx has increased to the first voltage level Vb. It is determined whether or not the battery is fully charged (full charge determination means). As a result, when the voltage value Vx is lower than the first voltage level Vb, the process returns to ST4, and the processing after ST4 is repeated.

On the other hand, in ST9, the voltage value Vx becomes the first voltage value.
If it is confirmed that the voltage level is equal to or higher than Vb,
In step ST10, the charging of the battery 22 is stopped by turning off the charging circuit 23 via the charging switching unit 33 (first charging stopping means). Thereafter, the process proceeds to the self-discharge control shown in FIG.

On the other hand, if the voltage value Vx of the RAM area m1 is not higher than the voltage value Vy of the RAM area m2 in ST8, the saturation counter n of the RAM area m3 is counted up by one in ST11, and then ST12. It is determined whether or not this counter n has reached a predetermined upper limit value [2]. If the counter n has not reached the upper limit value [2], the process returns to ST5, and the processing after ST5 is repeated.

On the other hand, when it is confirmed in ST12 that the counter n has reached the upper limit value [2], the charging of the battery 22 is stopped by turning off the charging circuit 23 via the charging switching section 33 in ST13. (Second charging stop means). Thereafter, in ST14, the voltage value Vx of the RAM area m1 is compared with a second voltage level Va preset in the EPROM area (abnormality determining means). As a result, when the voltage value Vx is higher than the second voltage level Va, the process proceeds to the self-discharge control shown in FIG. In ST14, the voltage value Vx
Is lower than the second voltage level Va, the battery 2
Since the charging is not performed normally due to the abnormality of the charging unit 2 or the failure of the charging circuit 23, the notification unit 35 is set as ST15.
The charging error is further notified (error notifying means), and this control ends.

When the self-discharge control starts, the charge control unit 31
First, the timer operation of the time t timer 37 is started in ST16. Next, in step ST17, the voltage Vx corresponding to the current charge amount of the battery 22 is detected via the voltage detection unit 32. In step ST18, whether the voltage value Vx has dropped to the second voltage level Va preset in the EPROM area is determined. Determine whether or not. If it is not descending, ST17
It is determined again whether the voltage value Vx of the battery 22 has dropped to the second voltage level Va.

When it is confirmed in step ST18 that the voltage value Vx of the battery 22 has dropped to the second voltage level Va, the timer operation of the time t timer 37 is stopped in step ST19 (discharge required time timer). . Thereafter, as ST20, the time measured by the time t timer 37,
That is, it is determined whether the self-discharge time t of the battery 22 is shorter than a self-discharge life value t1 preset in the EPROM area. If the self-discharge time t is not shorter than the self-discharge lifetime value t1, the process returns to ST3 of the charge control,
The charging circuit 23 is turned off and charging of the battery 22 is restarted (charge restarting means). If the self-discharge time t is shorter than the self-discharge life value t1 in ST20, it is determined that the life of the battery 22 has expired.
Is notified (lifetime notifying means), and this control is ended.

FIG. 5 shows an example of the voltage-time characteristic of the battery 22 when the charging of the battery 22 is controlled according to the present embodiment configured as described above. In this example, the ambient temperature in the environment where the battery 20 is placed is high, and the voltage Vx remains at the first voltage level V
This is the case where saturation occurs before reaching b. That is, as an initial state, the voltage Vx of the battery 22 is sufficiently lower than the second voltage level Va. In this state, when the power switch SW is turned on at time T0, the charging circuit 23 is turned on, and charging of the battery 22 is started.

In the charge control device 30, every time the time T measured by the time T timer 36 elapses (time T
1, T2, T3,...), The voltage value Vx of the battery 22 is detected and compared with the previously detected voltage value Vy. As a result, the current voltage value Vx is changed to the previous voltage Vy until time T8.
The battery 22 continues to be charged.

At time T9, the current voltage value Vx matches the previous voltage value Vy. Thereby, the saturation counter n becomes [1]. Next, even at time T10, the current voltage value Vx and the previous voltage value Vy match.
Thus, the saturation counter n becomes [2]. As a result, the charging circuit 23 is turned off, and charging of the battery 22 is stopped.

When the charging is stopped, the voltage value Vx of the battery 22 drops by self-discharge. Then, at time T1
When the voltage value Vx drops to the second voltage level Va at 1, the charging circuit 23 is turned on, and the charging of the battery 22 is restarted.

As described above, according to the present embodiment, the temperature of the atmosphere in which the battery 22 is placed is high, and the voltage Vx becomes the first voltage level Vb even if the battery 22 is charged continuously for a long period of time. Even when the battery is saturated before reaching, the charge is repeatedly turned off and on, so that the battery 22 can be prevented from being overdischarged by long-term continuous charge.

The ambient temperature of the environment in which the battery 22 is placed is low, and the battery 2
When the voltage value Vx reaches the first voltage level Vb, the charging is stopped in response to the voltage value Vx reaching the first voltage level Vb, and the voltage value Vx is reduced by the subsequent self-discharge. Since charging is resumed in response to the fall to the second voltage level Va, the battery 22
Is not overdischarged.

In the example shown in FIG. 5, when charging is not performed correctly due to an abnormality in the battery 22, a failure in the charging circuit 23, or the like, the current voltage value Vx of the battery 22 and the current voltage value Vx of the battery 22 at time T1 and time T2, respectively. Previous voltage Vy
As a result, the current voltage value Vx does not exceed the previous voltage value Vy twice consecutively. At this time, in the present embodiment, since the voltage value Vx is lower than the second voltage level Va, it is determined that the charging is abnormal, and the notification unit 35 is notified of the charging error. Therefore, it is possible to promptly notify the user of the charging abnormality due to the abnormality of the battery 22, the failure of the charging circuit 23, and the like.

In the example shown in FIG.
2 is stopped and self-discharge is started, the time t required for the voltage value Vx of the battery 22 to fall to the second voltage level Va from the stop of the charge is the time t timer 3
Timed by seven. This time t is long when the battery 22 is new, but becomes shorter as the battery 22 reaches the end of its life. Therefore, in the present embodiment, when the time t is longer than the self-discharge life value t1 set in advance, the charging of the battery 22 is restarted. However, when the time t is short, it is determined that the life of the battery 22 has expired. I am trying to inform you. Therefore, the user can be quickly notified of the life of the battery 22, and the image memory 1
It is possible to prevent a problem that data 1 cannot be protected from power failure.

In the above embodiment, the function of controlling the charge of the battery 22 for backing up the data of the image memory 11 in the facsimile apparatus has been described. However, the present invention is similarly applied to the control of the charge of a battery other than the battery 22. You can do it. In the embodiment, when the current voltage value Vx and the previous voltage Vy are compared with each other and the voltage does not exceed the previous voltage value, the saturation counter n is counted up, and when the count value becomes twice. Is determined to have been saturated, but may be determined to be saturated once, or may be determined to be saturated after three or more times.

In one embodiment, the battery 22
Are detected at the coincidence interval T, but the voltage value may be detected periodically and compared with the previous voltage value without necessarily detecting the voltage value at the constant interval T. For example, a rise rate from the previous voltage value to the present voltage value may be calculated, and the interval T may be shortened in proportion to the decrease in the rise rate. By doing so, it is possible to more quickly recognize that the voltage of the battery 22 has reached the first voltage level or is saturated.

[0042]

As described in detail above, according to the present invention,
Even if the battery is used in an environment with a high ambient temperature, overcharging can be prevented by continuous charging, and the life of the battery can be extended. In addition, when charging is not performed normally due to a failure in the charging circuit or the like, it is possible to promptly notify the user of the fact. Further, the life of the battery can be reliably detected and promptly notified to the user, thereby improving reliability.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a main configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a main area configuration of a storage unit in FIG. 1;

FIG. 3 is a flowchart showing a main control procedure executed by a charge control unit in FIG. 1;

FIG. 4 is a flowchart specifically showing a procedure of self-discharge control in FIG. 3;

FIG. 5 is a diagram showing an example of a voltage-time characteristic of a battery used for describing the operation of the embodiment.

FIG. 6 is a diagram showing a voltage-time characteristic example of a battery in conventional charge control.

FIG. 7 is a diagram showing an example of a voltage-time characteristic during self-discharge of a battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Main power supply 22 ... Battery 23 ... Charging circuit 30 ... Charge control device 31 ... Charge control unit 32 ... Voltage detection unit 33 ... Charge switching unit 34 ... Storage unit 35 ... Notification unit 36 ... Time T timer unit 37 ... Time t timer Department

Claims (6)

[Claims] 1. When charging of a battery is started, the voltage of the battery is periodically detected, and at each detection, the voltage is compared with at least a previous voltage value. Determines whether the voltage has risen to a preset first voltage level, and if the current voltage value has risen to the first voltage level or the current voltage value has not risen from the previous voltage value, charging is performed. And charging is resumed when the voltage of the battery drops to a second voltage level lower than the first voltage level due to self-discharge after the charging is stopped. 2. The battery charging control method according to claim 1, wherein the voltage value detected this time is not less than the second voltage level when the voltage value detected this time has not risen above the voltage value detected last time. A battery charge control method, comprising determining whether or not the battery voltage is lower than the second voltage level, and issuing a warning of a charge error. 3. The battery charging control method according to claim 1, wherein after charging is stopped, a time required for the voltage of the battery to fall to the second voltage level is measured, and the time is set in advance. A battery charge control method, wherein when the time is shorter than the time, the battery life is notified. 4. A voltage detecting means for periodically detecting a voltage of a battery being charged, and a voltage which is higher than the voltage value detected last time at each time when the voltage is detected by the voltage detecting means. A full charge determining means for determining whether the voltage value detected this time has increased to a first voltage level set in advance when the saturation determining means determines that the voltage value has increased from the previous time; First charge stopping means for stopping charging of the battery when the full charge determining means determines that the voltage has risen to the first voltage level; and charging of the battery when the saturation determining means determines that the voltage has not increased from the previous time. A second charge stopping means for stopping the charging, and after the charge is stopped by the first or second charge stopping means, the voltage of the battery is self-discharged to cause the first voltage to stop. Charge control device of the battery to be lowered to less than the pressure level second voltage level and resuming charging resuming means charging, characterized by comprising a. 5. The battery charge control device according to claim 4, wherein when the saturation determination means determines that the voltage has not increased from the previous time, it determines whether the voltage value detected this time has increased to the second voltage level. A battery charging control device comprising: an abnormality determining unit; and an error notifying unit that notifies a charging error when the abnormality determining unit determines that the voltage has not increased to the second voltage level. 6. The battery charge control device according to claim 4, wherein after the charge is stopped by said first or second charge stop means, it is necessary for the voltage of said battery to drop to said second voltage level. A discharge required time measuring means for measuring the time taken by the battery, and a life notifying means for notifying the life of the battery when the time measured by the time measuring means is shorter than a preset time. Charge control device.