JP3350153B2 - Memory effect detecting method and device, charging method and device, and portable facsimile device - Google Patents

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 detecting or charging a memory effect of a secondary battery such as a nickel cadmium (NiCd) battery.

[0002]

2. Description of the Related Art When a nickel cadmium battery or the like is charged after an incomplete discharge, a part of an electrode plate does not effectively act on charge / discharge, and a phenomenon in which an apparent capacity is reduced, that is, a so-called memory effect occurs. It is known.

FIG. 6 shows the discharge voltage characteristics of a nickel cadmium battery when a memory effect occurs and when it does not. When the memory effect does not occur, the battery voltage is almost stable from the start of discharge to the end of discharge as shown by the curve A in the small current discharge. However, when the memory effect occurs, at a small current discharge, as shown in a curve B, the capacity of 5
Before 0% is used up, the battery voltage falls below 1.0V which is the final voltage of the battery, and the apparent capacity (product of discharge current and discharge time) of the battery is greatly reduced. In a large current discharge, the effect of the memory effect is remarkable. As shown by a curve C, the battery voltage immediately falls below the end voltage after the start of the discharge, and the battery becomes practically unusable.

[0004] Here, the terminating voltage is a battery voltage at which discharge must be stopped, and is defined by a battery maker.
If the discharge is continued in a state where the voltage is lower than the cutoff voltage, a problem such as inversion of the polarity of some batteries occurs in the case of a battery pack.

As described above, when a memory effect occurs, a battery is hardly used in the case of a large current discharge. For example, a nickel cadmium battery or the like is used in a thermosensitive facsimile apparatus requiring a large current. If so, the occurrence of the memory effect is fatal. For example, when the memory effect occurs, the amount of electricity (product of current and time) that can be taken out of the battery immediately after charging is reduced, so that the number of recordable originals is extremely reduced, and in some cases, even one sheet cannot be recorded.
The recording speed becomes extremely slow due to insufficient current that can be instantaneously taken out.

Here, the use state of the battery in the battery-driven facsimile apparatus will be described. The battery is discharged upon reception. In general, the capacity of the battery is not completely used up in one reception, and the battery is half-discharged. However, the battery is usually charged in preparation for the next reception. This is a use situation in which the memory effect is likely to occur as described above. FIG.
FIG. 4 is a diagram schematically showing changes in battery voltage and capacity in such a use situation.

Elimination of the above-mentioned memory effect (refresh)
It is known that the battery may be discharged to a final voltage with a small current of a certain value or less.

FIGS. 5A and 5B show changes in battery voltage and capacity in the process of refreshing-completely charging a battery having a memory effect. A battery that has generated a memory effect recovers its original characteristics by performing a full charge after discharging the battery with a small current of a certain value or less to a final voltage in a refresh operation.

In order to perform this refresh,
As a premise, it is necessary to detect the occurrence of the memory effect, and the following methods have been conventionally devised.

The first method is a method of integrating the discharge current from charging to the battery voltage dropping to the final voltage, and determining that a memory effect has occurred when a certain capacity cannot be taken out.

In the second method, the battery voltage is periodically sampled during the discharge, so that when the memory effect occurs, the battery voltage drops by two steps at the end of the discharge (fourth step).
This is a method of detecting the occurrence of the memory effect by observing (see JP-A-4-186180).

In a third method, the battery is discharged for a certain period of time and the voltage at the end of discharging is stored, then the battery is charged, and the time until the completion of charging is shorter than the specified time and stored. It is determined that the memory effect has occurred when the post-discharge voltage is lower than or equal to a predetermined voltage.
issue).

[0013]

However, in the first method, it is difficult to know whether or not a memory effect has occurred unless the charged battery is completely used up. Therefore, the first method is incomplete as in a battery used in a facsimile apparatus. This is inconvenient for a battery that is charged after discharging.

The second method is also inconvenient in the case of a battery used in a device having a large load variation such as a facsimile machine, because if the load of the battery greatly varies, it is not possible to reliably detect the two-step drop due to the memory effect. It is.

In the third method, the remaining capacity at the start of charging is also taken into consideration depending on the voltage of the battery after discharging for a certain period of time. This is a method for determining the presence or absence. However, it is difficult to accurately detect the occurrence of the memory effect in a usage situation where the battery is charged after an incomplete discharge, such as a battery used in a facsimile apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its main purpose is to make it possible to reliably detect the presence or absence of a memory effect immediately after charging, and to check the progress of the memory effect. It is to prevent the battery from being used in the best condition.

[0017]

In order to solve the above-mentioned problems, in a preferred embodiment of the present invention, after a secondary battery such as a nickel cadmium battery is fully charged, it takes less than 1 second . A large current discharge is performed for a short time at a current exceeding the rated discharge current specific to the battery , and the battery voltage (V) at that time is measured. Then, a difference (RV-V) between the measured battery voltage (V) and the previously stored refresh voltage (RV) of the battery is compared with a predetermined voltage. When the difference is equal to or higher than the predetermined voltage, a memory effect occurs. It is determined that it has been performed. If it is determined that the memory effect occurs, electricity for refreshing the battery
A small current discharge is performed at a current smaller than the rated discharge current specific to the battery, a full charge is performed, and then a large current discharge is performed again. The battery voltage at that time is measured, and this is defined as a voltage after refresh (RV). Remember.

[0018]

In a secondary battery such as a nickel cadmium battery, when the memory effect occurs, the original characteristics are not restored even when the battery is fully charged, so that the battery voltage is significantly reduced at the time of a large current discharge after the full charge. On the other hand, when the memory effect is not generated, since the original characteristics of the battery are restored by the full charge, a decrease in the battery voltage at the time of discharging a large current after the full charge is small. According to the present invention, it is possible to determine the presence or absence of the memory effect in a fully charged state based on the characteristics related to the memory effect of the secondary battery.

Further, according to the present invention, when the memory effect is detected, refreshing and full charging are performed to restore the original characteristics of the battery, so that the progress of the memory effect is prevented and the battery is used in the best condition. it can.

Further, according to the present invention, when refreshing is performed, the post-refresh voltage (RV) is updated with the battery voltage at the time of large current discharge after full charge, thereby reducing manufacturing conditions and the number of charge / discharge cycles. The effect of variations in characteristics of individual batteries due to the difference can be eliminated, and the detection accuracy of the memory effect can be improved.

[0021]

FIG. 1 is a schematic block diagram of a battery charger according to one embodiment of the present invention. This battery charger 100
Is operated by an AC power supply, and has not only a function of charging a detachably set battery (NiCd battery or the like) 110 but also a function of detecting and refreshing a memory effect of the battery 110. In addition, DC power can be supplied to an external device.
18

In the battery charger 100, reference numeral 101 denotes a power supply circuit for producing a DC voltage stabilized from AC electric power, and connects a charging output 116 of the battery 110 and an external driving output 117 connected to the connector terminal 118. Have.
The power supply circuit 101 may have a known configuration including a rectifying / smoothing circuit for an AC voltage and a voltage stabilizing circuit.

The charging output 102 of the power supply circuit 101 is supplied to the battery 110 via the constant current circuit 102 and the switch 103.
Is connected to the positive electrode. The constant current circuit 102 includes a battery 110
This is a circuit for keeping the charging current for a constant value. The switch 103 is a switch for opening and closing the charging path of the battery 110, and is controlled by the controller 106.

Reference numeral 108 denotes an A / D converter for converting the voltage value of the battery 110 into a digital value. The output value is input to the comparator 107 and the controller 106. The comparator 107 compares the output value of the A / D converter 107 with the value given by the controller 106, and returns the comparison result to the controller. In order to store various values used for comparison of the comparator 107, the peak value storage memory 104, RV
There are a storage memory 105, an end voltage storage memory 114, and a memory effect determination voltage storage memory 115, which can be accessed by the controller 106. The values stored in each memory will be described later.

Reference numeral 111 denotes a refresh circuit for performing a low current discharge for refreshing the battery 110.
It is connected in parallel to battery 110 via switch 113.
The switch 113 is closed by the controller at the time of refresh, and at this time, the discharge path of the refresh circuit 111 is closed. Reference numeral 112 denotes a test load for flowing a large current for determining the memory effect of the battery 110, and reference numeral 109 denotes a switch inserted in series with the test load 112.
The switch 109 is closed by the controller 106 for a single time (several microseconds) immediately after the battery 110 is fully charged. Reference numeral 119 denotes a start button for starting the operation of the battery charger 100.

FIG. 2 is a schematic block diagram of a portable facsimile machine as an example of a device used in combination with the battery charger 100. The battery charger 100 according to the present embodiment can be generally used for charging a secondary battery such as a NiCd battery or a nickel-metal hydride battery, which has a problem of a memory effect.

The portable facsimile apparatus 200 is capable of performing facsimile communication using a battery as a power source and a wireless line, and includes a reading unit 201 for reading an original, a code for performing encoding or decoding of image data. A decoding unit 202, a radio interface unit 203 for interfacing with a radio line, an antenna 210 for transmitting and receiving a facsimile signal, a recording unit 204 for recording a received document, and detection of recording paper of the recording unit 204, etc. Sensor unit 206, an operation unit 29 for performing various operations such as transmission and reception, a system controller unit 205 of a program control system for controlling the entire apparatus, and a ROM storing fixed information such as a program of the system controller unit 205.
208, R used for temporary storage of various data
It comprises an AM 207, a battery section 211, and a connector terminal 212 connected to the connector 115 of the battery charger 100.
Such a configuration is the same as a general facsimile apparatus except that the power supply unit is replaced with the battery unit 211.

The battery section 211 is provided in the facsimile apparatus 200.
And a battery which can be charged by the battery charging unit 100. Discharge end detection means for detecting the end of discharge of the battery set in the battery unit 211 is provided. The discharge end detecting means is realized by software in the system controller unit 205 in the example shown here, but is provided as a hardware circuit inside or around the battery unit 211 and outputs the detection output to the system controller unit 2.
05 may be notified. The discharge end detection means of this software or hardware circuit constantly compares the battery voltage with the end voltage (a battery-specific value determined by the battery manufacturer), and outputs an end detection output when the battery voltage falls to the end voltage. The system controller 205 notifies the user of this (out of battery) to the outside using a display or the like of the operation unit 209.

Since the connector connection 212 is also connected to the same power supply wiring as the battery of the battery unit 211, the battery unit 211
Even when the battery is removed to charge the battery, the power supply 101 (FIG. 1) can be obtained by directly connecting the connector terminal 118 of the battery charger 100 to the connector 212 (or by connecting the connector via a cable with a connector or the like). The power can be further supplied and the facsimile apparatus 200 can be operated.

Next, the operation of the battery charger 100 will be described. FIG. 3 is a flowchart for explaining the operation. When the battery 110 used in the portable facsimile machine 200 or other equipment and required to be charged is set in the battery charger 100 and the start button 119 is pressed, the controller 106 performs the operation shown in FIG. Start control.

First, the controller 106 operates the switch 10
3 and the battery 110 is fully charged (ST
1). During this complete charging period, the controller 106
First takes in the output value (battery voltage) of the A / D converter 108 and writes it in the peak value storage memory 104.
After that, the storage value (peak value) of the peak value storage memory 104 is read and provided to the comparator 107, and the A / D converter 1
The output value (battery voltage) of the A / D converter 108 is compared with the output value (battery voltage) of the A / D converter 108 as a new peak value.
, And the operation of giving the rewritten peak value to the comparator 107 and comparing it again with the output value of the A / D converter 108 is periodically repeated.

As the charging progresses, the battery voltage gradually rises, and the peak value stored in the peak value storage memory 104 is updated and rises accordingly. When the battery 110 is charged to a fully charged state, the battery voltage drops in reverse (see FIG. 5). As the stored value of the peak value storage memory 104, the peak value of the battery voltage up to that time is stored. The system controller 106 determines completion of charging by detecting a drop (−ΔV) in the battery voltage after full charge, and
3 to end step ST6.

Immediately after completing the full charge, the controller 106 sets the switch 109 for a predetermined single time (several μ seconds).
A test pulse TP for closing the battery is generated, a large current is applied to the battery 110 through the test load 112 for a single time, and the battery voltage V at that time is taken in through the A / D converter 108 (ST2, ST3).

The amount of battery voltage drop due to the connection of the test load 112 is larger when the memory effect is generated. By paying attention to this characteristic, it is determined whether or not the battery 110 has a memory effect. That is, the controller 1
In step 06, the difference between the battery voltage V when the test load is connected and the voltage RV after refreshing (the value stored in the RV storage memory 105) is obtained, and this difference is compared with the memory effect determination voltage (memory 115).
(A value stored in the memory effect determination voltage), it is determined that the memory effect has not occurred when the difference is smaller than the memory effect determination voltage, and the memory effect has occurred when the difference is equal to or greater than the memory effect determination voltage. (ST
4).

If it is determined that the memory effect has not occurred, the charging operation is terminated, and the battery 110 is
0, and can be set in a device that uses it, for example, the battery unit 211 of the portable facsimile apparatus 200 in FIG.

When it is determined that the memory effect has occurred, the controller 106 performs a refresh operation of the battery 110 (ST5). That is, by closing the switch 113, the refresh circuit 111 is activated, and the battery 1
10 is discharged at a low current smaller than a certain current value specific to the battery. During this discharge, the controller 106 reads out the final voltage stored in the final voltage storage memory 114 and supplies the final voltage to the comparator 107. The comparator 107 compares the output voltage (battery voltage) with the output value of the A / D converter 108 (battery voltage). Let them do it.
As the discharge proceeds, the battery voltage gradually decreases. When the controller 106 determines from the comparison result of the comparator 107 that the battery voltage has dropped to the cutoff voltage, the controller 106 opens the switch 113 to terminate the discharge by the refresh circuit 111.

Next, the controller 106 proceeds to step ST.
A full charge operation of the battery 110 similar to that of the first battery is performed (ST
6) When this is completed, the test load 112 is connected to the battery 110 for a single time (several microseconds) to perform a large current discharge, as in step ST2, and the battery voltage at that time is passed through the A / D converter 108. At the same time, the comparison between the battery voltage and the cutoff voltage is performed by the comparator 107, and the comparison result is determined (ST7, ST8).

If the battery voltage at the time of the test addition connection is higher than the final voltage, the battery voltage taken in step ST7 is set as the refreshed voltage RV in the RV storage memory 10.
5 (ST9), and the charging operation ends. However, when the battery voltage when the test load is connected is equal to or lower than the cut-off voltage, it is determined that the battery 110 has reached the end of its life, and the fact is notified to the outside by lighting the display 121 or the like (ST1).
0), end the operation.

As described above, according to the battery charger 100, the refresh operation and the charging of the battery having the memory effect are automatically performed, and the battery can be used in the best condition while preventing the progress of the memory effect. .

Here, regarding the determination of the memory effect, FIG.
This will be further described with reference to FIG. FIG. 4 shows step ST in FIG.
2 shows a change in battery voltage when the test pulse TP is generated. (A) shows the case where the memory effect has not occurred in the battery, and (b) shows the case where the memory effect has occurred.

When no memory effect occurs, (a)
As described above, the drop amount of the battery voltage when the test load is connected is relatively small, and the difference between the battery voltage V at that time and the post-refresh voltage RV is smaller than the memory effect determination voltage. But,
When the memory effect has occurred, the drop in the battery voltage when the test load is connected is large, and the difference from the post-refresh voltage RV exceeds the memory effect determination voltage. In other words, the magnitude of the discharge current when the test load is connected and the memory effect determination voltage are selected so as to satisfy the above relationship depending on the presence or absence of the memory effect.

The post-refresh voltage RV can be set to a predetermined fixed value. However, even for batteries of the same type, considerable variations in battery voltage when a discharge test load is connected are recognized due to differences in manufacturing conditions, the number of charge / discharge cycles, and the like. Therefore, the post-refresh voltage R
If V is set to a fixed value, it is easily affected by such variations, and it is difficult to determine an optimum value. On the other hand, as described above, if the post-refresh voltage RV measured by applying a test load in a state of being fully charged after refreshing is used, a high-precision memory effect that eliminates the influence of individual battery variations is used. Detection becomes possible.

[0043]

As is clear from the above description, the present invention has the following effects. (1) According to the present invention, since the presence or absence of the memory effect can be determined immediately after the battery is fully charged, the method is more incomplete than the method based on the integrated value of the current until the battery is completely discharged or the charging time until the battery is fully charged. This is convenient for the purpose of detecting the memory effect of a battery in which discharging and charging are repeated. In addition, since the method is not a method of detecting a two-step drop of the battery voltage in the actual load state, it is possible to essentially avoid the influence of the battery load fluctuation. (2) According to the present invention, when refresh is performed by detecting a memory effect, the voltage after refresh (RV) is updated with the battery voltage at the time of large current discharge after full charge.
The effect of variations in the characteristics of individual batteries due to differences in manufacturing conditions and the number of heavy discharge cycles can be eliminated, and the memory effect can be detected with high accuracy. (3) According to the present invention, when a memory effect is detected,
Since the original characteristics of the battery are restored by performing refresh and complete charging, the battery effect can be prevented and the battery can be used in the best condition. As a result, in a device such as a battery-driven facsimile machine, it is possible to avoid performance degradation of the device due to the memory effect of the battery. (4) According to the charging device of the present invention, it is possible to take out the battery from the device and perform the charging and the memory effect detection while maintaining the device such as the facsimile device in an operable state.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a battery charging device that performs memory detection and battery charging according to the present invention.

FIG. 2 is a block diagram showing an example of a portable facsimile apparatus according to the present invention.

FIG. 3 is a flowchart for explaining the operation of the battery charger.

4A is a diagram illustrating a change in battery voltage due to a test load when a memory effect is not generated; FIG. 4B is a diagram illustrating a change in battery voltage due to connection of a test load when a memory effect is generated;

5A is a diagram showing a change in battery voltage in a process of refreshing-completely charging a battery in which a memory effect has occurred, and FIG. 5B is a diagram showing a change in battery capacity in the same process.

FIG. 6 is a diagram showing a change in discharge characteristics of a battery due to a memory effect.

FIG. 7 is a diagram showing changes in general voltage and capacity of a driving battery during operation of the facsimile apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Battery charger 101 Power supply circuit 102 Constant current circuit 103 Switch 104 Peak value storage memory 105 RV storage memory 106 Controller 107 Comparator 108 A / D converter 109 Switch 110 Battery 111 Refresh circuit 112 Test load 113 Switch 114 Termination voltage storage memory 115 Memory effect determination voltage storage memory 118 Connector terminal 200 Portable facsimile device 211 Battery unit 212 Connector terminal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 10/42-10/48 H02J 7/00-7/12 H04N 1/00 G01R 31/36

Claims (7)

(57) [Claims] 1. Step 1 of fully charging a secondary battery
And after the step 1, performing a large-current discharge of the secondary battery for a short time of less than 1 second with a current exceeding a battery-specific rated discharge current, and measuring a battery voltage (V) at that time. , The reference battery voltage (R
V) and a difference (RV-V) between the battery voltage (V) measured in Step 2 and a predetermined determination voltage to determine whether or not the memory effect of the secondary battery has occurred. And a memory effect detecting method for a secondary battery. 2. The method according to claim 2, wherein after the refresh and the full charge of the secondary battery are sequentially performed, the battery voltage at the time of performing the same large current discharge as in the step 2 is used as the reference battery voltage (RV). 2. The memory effect detecting method according to claim 1, wherein: 3. Step 1 of fully charging the secondary battery
And after the step 1, performing a large-current discharge of the secondary battery for a short time of less than 1 second with a current exceeding a battery-specific rated discharge current, and measuring a battery voltage (V) at that time. , The difference (R) between the pre-stored voltage after refresh (RV) and the battery voltage (V) measured in step 2
VV) is compared with a predetermined determination voltage, and when the difference is equal to or more than the determination voltage, it is determined that a memory effect has occurred. Battery for refreshing the secondary battery
Step 4 of performing a small current discharge with a current smaller than the intrinsic rated discharge current; Step 5 of performing a full charge of the secondary battery following the step 4; A method of charging a secondary battery, comprising: a step 6 for performing a large current discharge of the secondary battery and a battery voltage measurement; and a step 7 for storing the battery voltage measured in the step 6 as the refreshed voltage (RV) again. 4. A power supply means for supplying a charging current for a secondary battery, and a power supply means for exceeding the rated discharging current specific to the battery.
Test load means for discharging a large current with the obtained current, storage means for a post-refresh voltage and a memory effect determination voltage,
A step 1 of completely charging the secondary battery by a charging current supplied from the power supply means;
And a current exceeding the battery-specific rated discharge current through the test load means for a short time of less than 1 second.
In to perform the large current discharge, and the step 2 to obtain the battery voltage (V) at that time, and stored after a refresh is voltage (RV) in the storage means, obtained at the step 2 the battery voltage (V) And comparing the difference (RV-V) with the memory effect determination voltage stored in the storage means, and determining that the memory effect has occurred when the difference is equal to or greater than the memory effect determination voltage. And a control means for performing control comprising: 5. A power supply means for supplying a charging current to a secondary battery, and a power supply means for exceeding a rated discharging current specific to the battery.
A test load means for discharging a large current at a given current, and a battery-specific rated discharge power for refreshing the secondary battery.
Refresh means for discharging a small current with a current smaller than the current, storage means for a post-refresh voltage and a memory effect determination voltage, and causing the secondary battery to be fully charged by a charging current supplied from the power supply means. 1
And discharging the secondary battery through the test load means for a short time of less than 1 second following the step 1 to a battery-specific rated discharge.
Step 2 of causing the large current discharge to be performed with a current exceeding the current and obtaining the battery voltage (V) at that time; the voltage after refresh (RV) stored in the storage means; Difference from battery voltage (V) (RV−
Comparing V) with the memory effect determination voltage stored in the storage means, and determining that the memory effect has occurred when the difference is equal to or greater than the memory effect determination voltage;
If it is determined in step 3 that the memory effect has occurred, the secondary battery is discharged through the refreshing means.
Refreshing the secondary battery by causing a small current discharge at a current smaller than the intrinsic rated discharge current ;
Following the step 4, a step 5 of fully charging the secondary battery by the power supply means, and following the step 5, the secondary battery is battery-specific through the test load means for a short time of less than 1 second. Exceeded the rated discharge current
A control is performed which includes a step 6 of causing a large current discharge with a current and obtaining a battery voltage at that time, and a step 7 of storing the battery voltage obtained in the step 6 in the storage means as the post-refresh voltage. A charging device having control means. 6. The charging apparatus according to claim 5, further comprising an external terminal for supplying DC power from said power supply means to an external device. 7. A battery unit in which a secondary battery is set, and a terminal connected to the external terminal of the charging device according to claim 6, wherein the terminal or the secondary battery set in the battery unit is A portable facsimile machine supplied with operating power.