JPH077863A - Battery charger - Google Patents

Abstract

PURPOSE:To conduct the automatic discharging and charging in this order by starting the charging after discharge for the secondary battery installed first after the resetting of the main controller. CONSTITUTION:When the supply of a drive current is started from a constant current circuit 4 for a main controller 1, the main controller 1 is reset. Then, whether a secondary battery is installed between connecting terminals 5 and 6 is judged from a voltage generated at a potential dividing resistor 35 and, if the installation of the secondary battery is detected, a discharge signal 30 is output and discharge it a discharge circuit 21 is started. Next, when the end of discharge is detected from the drop in the output from the potential dividing resistor 35, a charge signal 13 is output and charging by a charging circuit 9 is started. Moreover, if a full charge is judged based on the output from the potential dividing resistor 35, a trickle charge signal 20 is output and shifting to trickle charging by a trickle charging circuit 14 occurs.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a charger.

[0002]

2. Description of the Related Art Currently, secondary batteries made of nickel / cadmium and nickel / hydrogen are widely used as driving sources for portable personal computers and video cameras.

Various methods have been proposed and put into practical use as charging methods for this type of secondary battery. As an example, for example, US Pat. Nos. 4,354,148 and 4387.
There is a so-called minus delta buoy system disclosed in the specification of No. 332. In this method, the charging is stopped when the voltage of the secondary battery exceeds the peak value and slightly decreases.

[0004]

On the other hand, this type of secondary battery has a memory effect. This memory effect means that a predetermined output cannot be obtained even though the secondary battery has a remaining amount by repeating halfway discharge and charging without completely discharging the secondary battery. That is.
A way to prevent this memory effect is to occasionally completely discharge the secondary battery. For this reason, some chargers currently on the market are equipped with a discharging circuit.

However, since the conventional charger of this type has a structure in which charging and discharging are switched by a manual switch, the user is required to perform a switching operation of discharging and charging, which is not convenient.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is characterized by a charger that can charge a secondary battery by a constant current and that has the secondary battery detachable. A constant current circuit for generating a constant current, a charging circuit for supplying a constant current generated by the constant current circuit as a charging current for the secondary battery, and a discharging circuit for discharging the secondary battery. A main controller having means for controlling the above-mentioned circuits and for detecting attachment / detachment of the secondary battery, wherein the main controller first detects the attachment by the detector after resetting itself. The secondary battery is discharged by controlling the discharging circuit first, and then is charged by controlling the charging circuit.

[0007]

With this structure, the secondary battery that is initially installed after the main control unit is reset is discharged and then charged.

[0008]

1 is a partial block circuit diagram showing an example of a charger according to the present invention. In the figure, (1) is a main control unit including, for example, a microcomputer, and the main control unit controls each unit described below based on a built-in control program.

(2) is a rectifying / smoothing circuit composed of a diode bridge or the like, and this circuit converts an alternating current supplied from an AC terminal into a direct current, and after smoothing, selects the primary winding of the transformer (3) To supply (4) is a constant current circuit, which converts the current induced on the secondary winding side of the transformer (3) into a DC constant current having a predetermined current value under the control of the main control unit (1). Convert and output. Although not shown in the figure, the constant current circuit (4) also supplies a drive current to the main controller (1). (5) and (6) are + -connection terminals to which a secondary battery (not shown) made of nickel-cadmium or nickel-hydrogen is detachably connected, and these terminals are connected to the constant current circuit (4). ) The first side and the second side of the constant current output are the first and second current paths (7).
It is connected via (8).

Reference numeral (9) is a charging circuit arranged in series in the first current path (7), which circuit comprises a first transistor (10) for switching and resistors (11) and (12),
According to the charging signal (13) from the main controller (1), the first
The on / off of the transistor (10) is controlled. That is, when the first transistor (10) is turned on, the output of the constant current circuit (4) can be supplied to the connection terminal (5) via the first transistor (10).

Reference numeral (14) is a trickle charging circuit connected in parallel to the charging circuit (9), which circuit comprises a second transistor (15) for switching and resistors (16) (17) connected to the base side thereof. And resistor for adjusting current (18)
(19) and the trickle signal (20) from the main controller (1) controls the on / off of the second transistor (15). That is, when the second transistor (15) is turned on, the output of the constant current circuit (4) is the second transistor (1).
5) and connection terminals (5) via resistors (18) and (19)
Can be supplied to.

Reference numeral (21) is a discharge circuit connected between the connection terminals (5) and (6), and the circuit is connected to the bases of the third and fourth transistors (22) and (23) and the third transistor (22). Connected backflow prevention Zener diode (2
4) (25) and resistors (26) to (29). The discharge circuit (21) receives the discharge signal (30) from the main control unit (1) and the third and fourth transistors (22).
On / off of (23) is controlled. That is, the third and the fourth
When the transistors (22) and (23) are turned on, the output of the secondary battery connected to the connection terminals (5) and (6) flows through the third transistor (22) and the resistor (26).
At this time, power is consumed due to heat generated by the third transistor (22), and the secondary battery can be discharged.

Reference numeral (31) is a first light emitting diode, which is connected to be capable of emitting light when the fifth transistor (32) is turned on by the charging signal (13).
(33) is a second light emitting diode, and the light emitting diode is connected to be capable of emitting light when the sixth transistor (34) is turned on by the discharge signal (30).

Therefore, the first light emitting diode (31)
Lights up during charging of the secondary battery via the charging circuit (9),
On the other hand, the second light emitting diode (33) has a discharge circuit (21).
Lights while the secondary battery is being discharged by. It should be noted that by making the light emitting colors of the respective light emitting diodes (31) and (33) different, it is possible to make the charging / discharging operation easily visible.

Reference numeral (35) is a voltage dividing resistor connected to the connection terminal (5), and the main control section (1) detects the battery voltage of the secondary battery based on the voltage across the voltage dividing resistor. .

FIG. 2 is a flow chart showing the control operation of the main controller (1), and the operation of this embodiment will be described below based on this chart.

First, in step S1 the main control unit (1)
On the other hand, when the supply of the drive current from the constant current circuit (4) is started, the main controller (1) is reset. In the subsequent step S2, the main control unit (1) resets the built-in flag F to "0". This flag F becomes "1" when the secondary battery is discharged, as will be apparent from the description below.
In step S3, it is determined whether or not a secondary battery is mounted between the connection terminals (5) and (6). This determination is performed based on the voltage generated by the voltage dividing resistance (35) when the secondary battery is mounted, and is based on this. When attachment is detected in this determination, the flag F is set to "1" in step S4.
Or not. In this determination, "F =
If it is determined to be "0", the process proceeds to step S5.

In step S5, the secondary battery connected between the terminals (5) and (6) is discharged. Specifically, the discharge circuit (21) outputs the discharge signal (30).
Only the charging circuit (9) and the trickle charging circuit (14) are turned off and the discharging circuit (21) of the secondary battery starts discharging. At this time, since the second light emitting diode (33) also conducts and emits light by the discharge signal (30), it can be easily visually recognized that discharging is in progress.

At the subsequent step S6, it is determined whether or not the discharge is completed. When the secondary battery is completely discharged, the output of the voltage dividing resistor (35) also decreases, and this determination is made based on this. If the discharge end is detected by this determination, the process proceeds to S9.
Go to step. On the other hand, if it is determined that the discharge has not ended, the process proceeds to step S7.

In step S7, the presence / absence of a secondary battery is determined in the same manner as step S3. If the secondary battery is continuously attached, the process is returned to step S6 to continue discharging. on the other hand,
When it is determined that the secondary battery has been removed, the process proceeds to step S8 and the post-processing in which the flag F is set to "1" is returned to step S3.

If it is determined in step S4 that "F = 1" or if it is determined in step S6 that the discharge has ended, the process proceeds to step S9. Charging is started in step S9. Specifically, first, only the charging signal (13) is output to make the charging circuit (9) conductive, and the trickle charging circuit (14) and the discharging circuit (21) are turned off to start charging the secondary battery. To do.
At this time, since the first light emitting diode (31) is also turned on by the charging signal (13) and lights up, it can be visually recognized that charging is in progress.

In the subsequent S10 step, the presence or absence of the secondary battery is determined in the same manner as in the S3 step, and when it is determined that the secondary battery is removed, the output of the charging signal or the like is stopped and the post-processing for ending the charging is performed. Proceed to step S8. On the other hand, if it is determined that the device continues to be worn, the process proceeds to step S11. In step S11, it is determined based on the output of the voltage dividing resistor (35) whether the battery is fully charged. If it is determined that the battery is fully charged, the trickle charging signal (20) is output instead of the charging signal (13) and the trickle charging is performed. Move on to. On the other hand, when it is determined that the full charge has not been reached, the output of the charge signal (13) is continued. When the process of step S11 is completed, the process returns to step S10.

To summarize the above operation in a simple manner, the secondary battery mounted after or after the reset of the main control unit (1) is automatically discharged and charged automatically. In addition, when the battery removed during or after the discharge is reattached, the charging is immediately started without discharging.

In this embodiment, after the main control unit (1) is reset, only the charging operation is always performed on the secondary battery that has been mounted more than once. By providing a reset means for resetting the control unit (1), the secondary battery mounted after the second time is also discharged.
It can be charged automatically.

[0025]

According to the present invention, discharging and charging can be automatically performed on the mounted secondary battery in that order, so that the operation is simplified. Further, there are cases where normal discharge takes about 10 hours, and when there is no time to discharge for a long time, charging can be started immediately by removing the secondary battery during discharging and then reattaching it. .

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart for explaining a control operation of this embodiment.

[Explanation of symbols]

 1 Main control unit 4 Constant current circuit 9 Charging circuit 21 Discharging circuit

Claims (1)

[Claims] 1. A charger capable of charging a secondary battery with a constant current and having the secondary battery detachable, the constant current circuit generating a constant current, and a constant current circuit generated by the constant current circuit. A charging circuit that supplies a current as a charging current to the secondary battery, a discharging circuit for discharging the secondary battery, and a control circuit for controlling each circuit and mounting the secondary battery.
A main control unit having a means for detecting non-attachment, the main control unit first controlling the discharge circuit for a secondary battery whose attachment is detected by the detection unit first after resetting itself. The charger is characterized in that it is discharged by, and then is charged by controlling the charging circuit.