JPH0759265A - Battery circuit - Google Patents

Abstract

PURPOSE:To provide a battery circuit which can bring out the performances of a plurality of secondary batteries sufficiently. CONSTITUTION:A charging amount detecting section 24 detects the charged state and the discharged state (e.g. end of discharge) of two sets of secondary batteries 9a, 9b. When the charging operation is required, a switch control circuit 22 controls switch circuits 23a, 23b to charge the two sets of secondary batteries 9a, 9b individually from a charging power supply 1. Outputs from the two sets of secondary batteries 9a, 9b are taken out individually through the switch circuits 23a, 23b and fed to a load circuit 2. In other words, the secondary batteries 9a, 9b are charged/discharged individually through the switch circuits 23a, 23b and the charging operation is effected only after the discharge operation is finished completely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery circuit, and more particularly to a battery circuit which uses a plurality (for example, two sets) of secondary batteries and is suitable for use in, for example, a mobile phone device.

[0002]

2. Description of the Related Art Recently, batteries are used in many fields. For example, a current digital wireless mobile terminal device (for example, PHP (Personal Handy Phone)) or a portable video camera device uses a battery (particularly, a secondary battery) as a means for supplying power. Some portable telephone devices use a plurality (usually two sets) of batteries connected in parallel in order to secure a long call because of the talk time. Similarly, some portable video camera devices also use two sets of batteries connected in parallel so as to ensure long-time imaging.

As a circuit example of a conventional battery circuit used in a portable telephone device or the like, for example, one shown in FIG. 3 is known. In FIG. 3, reference numeral 1 is a charging power source, which can supply a DC power source of a rectified predetermined voltage after transforming AC100V into a predetermined voltage, for example. A load circuit 2 is, for example, a mobile phone device. Reference numerals 3 and 4 are constant current elements with open / close switches, and 5 to 8 are diodes. A battery set 9 has two sets of secondary batteries 9a and 9b. Reference numeral 10 is a charge amount detection unit, and two sets of secondary batteries 9
On / off control (opening / closing control) of the constant current elements 3 and 4 is performed in order to control the charging of each of a and 9b.
Specifically, during charging, the constant current elements 3 and 4 are turned on to bring the secondary batteries 9a and 9b into a charged state, and when the completion of charging is detected, control is performed to turn off the constant current elements 3 and 4.
a and b are charging side terminals, and c and d are load side terminals.

In the example of FIG. 2, the charging side terminals a and b are directly connected to the load side terminals c and d so that the load circuit 2 can operate by receiving electric power from the charging power source 1 even during charging. The lines 11 and 12 are connected to the. When the charging power source 1 is dedicated to charging and does not require the operation of the load side during charging, the charging side terminals a and b directly connect the load side terminals c and d to the line 11, The configuration in which 12 is connected may be omitted.

The operation during charging will be described. When charging, the operator inserts the charging-side terminals a and b into the charging power source 1 to forcibly start charging. When charging is complete,
When the operator pulls out the charging side terminals a and b from the charging power source 1, the charging is forcibly terminated. Now, at the time of charging, a loop of the charging power supply 1 from the charging side terminal a → constant current elements 3 and 4 (on state) → diodes 5, 7 → battery set 9 → charging side terminal b is formed, and Two
The pair of secondary batteries 9a and 9b are charged. In this case, there are two sets of the secondary batteries 9a and 9b, but as is clear from this circuit, the independent constant current elements 3,
4 is charged via the secondary battery 9a and the secondary battery 9
Even if there is a difference in the remaining capacity between b and b, the battery is charged with a current according to each. For the completion of charging, the charge amount detecting unit 10 detects the charging completion state for each secondary battery 9a or secondary battery 9b, and the corresponding constant current element 3 or constant current element 4 is detected.
By turning off. On the other hand, the discharging operation will be described. At the time of discharging, current is taken out from the battery set 9 and supplied to the load circuit 2. At this time, the one having a higher battery voltage by the diode 6 or the diode 8 (that is, one having a large remaining charge). The secondary batteries 9a and 9b are selected and current is supplied to the load circuit 2 via the load side terminals c and d. Therefore, when the capacity of one of the secondary batteries decreases, the other secondary battery takes charge of the current supply to the load, so that the discharge current is alternately consumed by the two sets of secondary batteries 9a and 9b, and both of them are substantially equal. Will be discharged.

[0006]

By the way, the above-mentioned 2
The secondary batteries 9a and 9b generally have a memory effect.
The memory effect means that unless the secondary battery is completely discharged, charging is not sufficiently performed and the function as the secondary battery is impaired. Therefore, if charging is started again before the secondary batteries 9a and 9b reach the discharge end voltage (voltage at which the memory effect is cleared), the battery life will be shortened. However, in the conventional battery circuit of the related art, in some cases, the charging of the two sets of secondary batteries 9a and 9b may be started again before the discharge end voltage is reached.
There was a problem that the life of both batteries in the set would be shortened.

For example, before the secondary batteries 9a and 9b reach the end-of-discharge voltage, the operator does not understand the phenomenon of the memory effect and usually does not know that there is such a phenomenon. However, the charging side terminals a and b are inserted into the charging power source 1 to start charging. In such a case, charging is forcibly started and the battery life is shortened due to the memory effect. Incidentally, the conventional secondary batteries 9a, 9b
In general, a sensor for detecting whether or not the discharge end voltage has reached the discharge end voltage is not provided (for example, because of cost increase), and therefore the operator cannot judge the discharge state.

Since the battery performance has "variation", the two sets of secondary batteries 9a and 9b should be used in charge / discharge cycles (battery charge / discharge characteristics) suitable for each. Since the two sets of secondary batteries 9a and 9b have a parallel circuit configuration in which charging / discharging is performed at the same time, it is expected that both of them can be satisfied by adjusting to either cycle. Both secondary batteries 9a,
It was difficult to make full use of the performance of 9b. Further, there is a drawback that it is not possible to easily determine which battery is deteriorated and eventually the two sets of secondary batteries 9a and 9b are integrally replaced as a pair. Therefore, it was expensive. In addition, since there is a voltage drop in the diodes 5 and 7, there is a drawback that the operating voltage of the charge amount detection unit 10 is lowered. From the above, it is difficult for the conventional battery circuit to sufficiently bring out the performance of the two sets of secondary batteries.

Therefore, an object of the present invention is to provide a battery circuit which can sufficiently bring out the performance of a plurality of batteries.

[0010]

To achieve the above object, the battery circuit according to the present invention is capable of at least individually charging a plurality of secondary batteries by a charging power source, and at the same time, these plurality of secondary batteries can be charged. Is a battery circuit capable of at least individually taking out the output of each of the plurality of secondary batteries and supplying it to the load device, the charge amount detecting means for detecting the charge state and the discharge state of each of the plurality of secondary batteries, and the plurality of secondary batteries. On the other hand, it is characterized by comprising switch means capable of individually switching between charging and discharging, and switch control means for controlling the operation of the switch means based on the output of the charge amount detecting means. Moreover, as a preferable aspect,
A display means capable of performing a predetermined display is provided, and this display means is
The operating statuses of the plurality of secondary batteries may be individually displayed on the outside based on the operation of the switch control means.

[0011]

In the present invention, the charge amount detecting means detects the charge state and discharge state (for example, discharge completion point) of each of the plurality of secondary batteries, and when charging is required, the switch control means causes the switch means. Is controlled, and the plurality of secondary batteries are at least individually charged from the charging power source. Further, the outputs of the plurality of secondary batteries are at least individually taken out through the switch means and supplied to the load device. Therefore, it is possible to individually switch the charging / discharging with respect to the plurality of secondary batteries by the switch means, and to perform the charging only after the completion of the complete discharging. As a result, even if there are variations in the battery performance, charging / discharging is performed according to each, and the performance of the plurality of batteries can be fully brought out.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a battery circuit according to the present invention, which is an example applied to a portable telephone device. In the description of FIG. 1, the same components as those in FIG. 3 of the conventional example will be denoted by the same reference numerals and redundant description will be omitted. In FIG. 1, 21 is a constant current element with an open / close switch, 22 is a switch control circuit, 23 is a switch unit, 24 is a charge amount detection unit, and 25 is a display unit. Unlike the conventional example, only one constant current element 22 is arranged, and the constant current element 22 is commonly used for a plurality (two in this embodiment) of secondary batteries 9a and 9b.

An example of the constant current element 21 is shown in FIG.
You In FIG. 2, 21a is an input terminal and 21b is an output terminal.
The child 21c is a control terminal. Also, V_inIs the input voltage,
V_out is the output voltage, V_contIs the control voltage, V_RIs the set voltage,
V_BEIs the voltage between the base and emitter, I₀Is the charging current,
R₁, R₂Is a voltage setting resistor, R_SIs a current limiting resistor, R_c
Is the control resistor, Q₁Is a current limiting transistor, Q₂Is
It is a switch control transistor. Now the control voltage V
_contIs "L" level, it is a transistor for switch control.
Q 2 is off and the set voltage V_R= Input voltage V_inTona
It Therefore, the current limiting transistor Q₁Is cut o
There is no charge current. On the other hand, the control voltage V
_contWhen it goes to “H” level, the transition for switch control
Star Q₂Turns on and the set voltage V_RIs the value expressed by the following formula
become. V_R≒ (V_in× R₂) / (R₁+ R₂) By this, the charging current I₀Is as follows. I₀≒ (V_in-V_R-V_BE) / R_S≈ Constant Therefore, the charging current I having the value expressed by the above equation₀To the battery
Supplied. In this way, the switch control transistor
Q₂Charge or charge depending on the level applied to the base of
The control of stopping the power is performed.

The input side of the constant current element 21 is connected to the charging side terminal a, and the output side of the constant current element 21 is connected via the line 31 to the switch circuit 2.
3 is connected to the charging side contact. The discharge side contact of the switch circuit 23 is directly connected to the load side terminal c via the line 32. The charging side terminal b and the load side terminal d are directly connected via a line 33. The charge amount detection unit (charge amount detection means) 24 includes two sets of secondary batteries 9a and 9a.
For detecting the charging state and discharging state of each of the secondary batteries 9b and 9b, for example, the charging currents of the secondary batteries 9a and 9b are monitored, and when the charging currents are below a certain value, it is determined that the charging is completed and the secondary batteries 9a and 9b.
The discharge voltage of b is monitored, and when it is below a certain value (below the discharge completion point), it is judged that the discharge is completed. The detection signal of the charge amount detector 24 is input to the switch control circuit 22. The switch control circuit (switch control means) 22 includes a charge amount detection unit 2
The operation of the switch section (switch means) 23 is controlled based on the detection signal from the switch 4. The switch unit 23 includes two sets of a switch circuit 23a and a switch circuit 23b. The switch circuits 23a and 23b are capable of individually switching charging / discharging with respect to the two sets of secondary batteries 9a and 9b. One switch and three switching contacts (charging contact, neutral contact, It has a discharge contact).

The switch circuit 23a has a charging contact, a neutral contact, and a discharging contact, and FIG. 1 shows a state in which the switch is switched to the charging contact and connected to the constant current element 21 via the line 31. There is. The neutral contact is provided, for example, when the secondary battery 9a is taken out from the battery set 9, and at this time, the switch is at a position connected to the neutral contact. The discharge contact connects the secondary battery 9a to the load side terminal c via the line 32. Similarly, the switch circuit 23b has a charging contact, a neutral contact, and a discharging contact, and FIG. 1 shows a state in which the switch is switched to the discharging contact and connected to the load side terminal c through the line 32. There is. The neutral contact is provided, for example, when the secondary battery 9b is taken out from the battery set 9, and at this time, the switch is at a position connected to the neutral contact. The charging contact connects the secondary battery 9b to the constant current element 21 via the line 31.

The switch control circuit 22 includes a charge amount detector 24.
Based on the detection signal from the switch, the contacts of the switches of the two sets of the switch unit 23a and the switch circuit 23b are switched to control the charging or discharging of the secondary batteries 9a and 9b of the battery set 9. The display unit (display means) 25 is for externally displaying, based on a signal from the switch control circuit 22, whether charging or discharging is completed in correspondence with the operating conditions of the switch circuits 23a and 23b. To be done. It should be noted that the display unit 25 forms a pair 2
For each of the secondary batteries 9a and 9b, a display such as charging or completion of discharging is individually performed.

Next, the operation will be described. [At Charging] Now, the secondary batteries 9a and 9b are both completely discharged. At the time of charging, the operator inserts the charging-side terminals a and b into the charging power source 1, whereby the charging is forcibly started. In the charging process, the charge state of each of the secondary batteries 9a and 9b is first detected by the charge amount detecting section 24. However, since neither of them is fully charged at the beginning, based on the detection signal of the charge amount detecting section 24. Switch control circuit 22 is 2
Control is performed to switch the contacts of the switches of the set of the switch unit 23a and the switch circuit 23b to the charging side.

Here, for convenience, it is assumed that one of the secondary batteries 9a is set to start charging. In this case, the switch control circuit 22 switches the switch of the switch circuit 23a to the charging contact, and the other switch circuit 2
Switch the switch of 3a to the neutral contact. This allows
In the battery set 9, a loop is formed from the charging power source 1 to the charging side terminal a → constant current element 21 (on state) → line 31 → switch circuit 23a → battery set 9 secondary battery 9a → charging side terminal b. One of the secondary batteries 9a is charged. At this time, unlike the conventional case, the diode is not provided on the charging line, and the problem that the operating voltage of the charge amount detection unit 24 is lowered due to the voltage drop of the diode is eliminated. Also, during charging, the display unit 2
The display of "charging" is performed by 5. Therefore, the operator can confirm the operation by displaying "charging". At this time, it is preferable to display so that it can be recognized that one of the secondary batteries 9a is being charged. For example, when the secondary battery 9a is represented by the battery A, the display unit 2
5 displays “Battery A is charging”.

[During Discharging] When the secondary battery 9a is charged and the end of charging is detected by the charge amount detector 24, the switch control circuit 22 controls the switch of the switch circuit 23a to switch to the discharging contact. At this time, when the load circuit 2 is connected, a loop is formed from the secondary battery 9a to the switch circuit 23a → the line 32 → the load side terminal c → the load circuit 2 → the load side terminal d, and the power is supplied to the load. , The load operates. During discharging, the display unit 25 displays "Discharging". Therefore, the operator can confirm the operation on the display of "during discharge". At this time, it may be displayed so that it can be recognized that one of the secondary batteries 9a is being discharged. For example, the secondary battery 9a
Is represented by the battery A, the display unit 25 displays “Battery A is discharging”.

Further, in this case, the switch control circuit 22 controls the switch of the switch circuit 23a to switch to the charging contact in parallel with the switch switching control of the switch circuit 23a. As a result, a loop is formed from the charging power source 1 to the charging side terminal a → constant current element 21 (ON state) → line 31 → switch circuit 23b → rechargeable battery 9b of the battery set 9 → charging side terminal b, and The other secondary battery 9b in the set 9 is charged. At this time, similarly to the conventional case, no diode is provided on the charging line, and there is no problem that the operating voltage of the charge amount detection unit 24 is lowered due to the voltage drop of the diode. Similarly, during charging, the display unit 25 displays "charging". At this time, it may be displayed so that the other secondary battery 9b can be recognized as being charged. For example, the secondary battery 9b is represented by the battery B, and the display unit 25 displays “Battery B is being charged”.

When the secondary battery 9b is charged and the charge amount detecting section 24 detects the end of charging, the switch control circuit 22 controls the switch of the switch circuit 23b to switch to the neutral contact. This is the switch circuit 2
Since the switch 3a is switched to the discharging contact, it is possible to prevent the discharge from being hindered by the potential difference between the secondary batteries 9a and 9b and to prevent the potential difference from being absorbed between the secondary batteries 9a and 9b. This is because. By these control operations, when charging is completed, even if the charging side terminals a and b are connected (plugged in) to the charging power source 1, each 2
The secondary batteries 9a and 9b are not charged. At this time, the display section 25 displays "charge completed". Normally, when charging of both the secondary batteries 9a and 9b is completed, the operator pulls out the charging side terminals a and b from the charging power source 1.

[Operation at Discharge Completion Point] As described above, when one secondary battery 9a is in the discharging state and the other secondary battery 9b is in the charging state, the secondary battery 9a that has been continuously discharged is at the discharging completion point ( For example, when approaching a constant discharge completion voltage), the charge amount detection unit 24 detects the discharge completion point of the secondary battery 9a,
A detection signal of the discharge completion point is sent to the switch control circuit 22. In response to this detection signal, the switch control circuit 22 controls the switch of the switch circuit 23a to switch to the charging contact, and at the same time controls the switch of the switch circuit 23b to switch to the discharging contact. As a result, this time, the load device 2 becomes the secondary battery 9 of the battery set 9.
b continues to operate while receiving power from the secondary battery 9
a starts charging operation. The same applies to the control when the other secondary battery 9b approaches the discharge completion point. When the secondary battery 9a that has been discharged reaches the discharge completion point, the display unit 25
The display of "discharge completed" is performed. At this time,
It is preferable to display the secondary battery 9a so that it can be recognized that the secondary battery 9a is completely discharged. For example, replace the secondary battery 9a with the battery A
The display unit 25 displays “Battery A discharge completed”.

As described above, in the present embodiment, the secondary battery 9a or 9b is charged by the battery 9a or 9b.
Is only performed after the discharge completion point. Further, the power supply to the load device 2 starts only after one of the pair reaches the discharge completion point. That is, charging is not started unless the secondary battery 9a or 9b is completely discharged. Therefore, charging is performed after the voltage reaches a level at which the memory effect is cleared, so that charging can be sufficiently performed. As a result, even if there are “variations” in the performance of the secondary batteries 9a and 9b, charging / discharging is performed according to each, so that the performances of the secondary batteries 9a and 9b can be fully brought out, and The life can be extended. Therefore, it is possible to meet the demand for extending the usage time of the load device (mobile phone device) using the battery circuit of the present invention compared to the present situation.

Further, even when either the secondary battery 9a or 9b is deteriorated and needs to be replaced, the secondary batteries 9a and 9b forming a pair perform the alternating operation of charging and discharging, and therefore are deteriorated. It is easy to discriminate the existing batteries, there is no problem that they are integrally replaced as a pair, and only the deteriorated battery can be replaced, which is advantageous in terms of cost. Furthermore, the operation status of the secondary batteries 9a and 9b is displayed on the display unit 2.
Since it is displayed externally by 5, the situation can be grasped at a glance. It should be noted that a plurality of display units 25 may be provided corresponding to the number of secondary batteries, or one display unit 25 may be displayed with a different pattern. Further, the display means is not limited to the configuration incorporated in this battery circuit, and for example, a display signal is transmitted from the battery circuit to the CPU of the load device (mobile phone device) and the display device such as an LED or a liquid crystal arranged in the load device. Alternatively, the display data processed by the CPU may be displayed.

In the above embodiment, an example in which two sets of secondary batteries are combined has been described, but it goes without saying that the present invention can be applied to secondary batteries having more than two sets. In this case, as the number of secondary batteries increases, only one constant current element 21 is required, and therefore more economical merit occurs. Further, the application field of the present invention is not limited to the mobile phone device, but can be applied to, for example, a portable video camera device, as well as other portable devices.

[0026]

According to the present invention, the charging / discharging of each of the plurality of secondary batteries is individually switched by the switch means so that the charging is performed only after the completion of the complete discharging. Therefore, the battery is charged after reaching the voltage at which the memory effect is cleared, and charging can be sufficiently performed. Therefore, even if there is "variation" in the performance of the secondary battery, charging / discharging is performed according to each, and the performance of the secondary battery can be fully brought out and the life of the battery can be lengthened. As a result, it is possible to meet the demand for extending the usage time of a load device (for example, a mobile phone device) using the battery circuit of the present invention as compared with the current situation. Further, when one of the plurality of secondary batteries deteriorates and needs to be replaced, the other secondary battery performs alternating operation of charging and discharging, so that the deteriorated battery can be easily identified.
There is no inconvenience of replacing them as a pair, and only the deteriorated battery can be replaced, which is advantageous in terms of cost. Further, according to the second aspect of the invention, since the operation status of the secondary battery is displayed outside by the display means, the operation status of the secondary battery can be grasped at a glance.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a battery circuit according to the present invention.

FIG. 2 is a circuit diagram showing an example of a constant current element of the same embodiment.

FIG. 3 is a block diagram of a conventional battery circuit.

[Explanation of reference numerals] 1 power source for charging 2 load circuit 9 battery set 9a, 9b secondary battery 21 constant current element 22 switch control circuit (switch control means) 23 switch section (switch means) 24 charge amount detection section (charge amount detection Means) 25 display unit (display means)

Claims (2)

[Claims] 1. A battery circuit capable of at least individually charging a plurality of secondary batteries with a charging power source and at least individually outputting the outputs of the plurality of secondary batteries and supplying the outputs to a load device. And a charge amount detecting means for detecting a charge state and a discharge state of each of the plurality of secondary batteries, and a switch means capable of individually switching charge / discharge with respect to the plurality of secondary batteries, A switch control means for controlling the operation of the switch means based on the output of the charge amount detecting means; 2. A display means capable of performing a predetermined display is provided, and the display means is capable of individually displaying the operating states of the plurality of secondary batteries to the outside based on the operation of the switch control means. The battery circuit according to claim 1.