JPH0118655B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a charging completion display for an automatic charging device that charges a secondary battery.

Conventional configuration and its problems The conventional charging method for secondary batteries is generally a constant current charging method, and the charging display is often limited to only charging and energizing. To ensure the completion of charging and the amount of charge, the user had to check the charging time himself and mark the charging as complete. Furthermore, in automatic charging devices that can perform rapid charging, the more clearly the charging completion display is attempted to shorten the charging time, the more problems that must be solved. Charging and energization indication in a conventional rapid automatic charging device has been performed using a circuit configuration as shown in FIG. That is, the main charging circuit is constructed by connecting the battery B to be charged to the power supply rectifier circuit 1 via the automatic charging control circuits 2 and 3, and connecting the backflow prevention diode _D1 to the negative side of the battery B to be charged. ,
Then, the voltage is dropped by the resistor R ₁ inserted in this main charging circuit, and the resistor R ₂ and light emitting diode D ₂ are connected in parallel with this resistor R ₁ , and charging and energization are performed by lighting the light emitting diode D ₂ . was displayed. Above light emitting diode D ₂
The light emitting diode _D2 can be lit under the condition that the voltage drop across the resistor _R1 is equal to or higher than the forward voltage value of the light emitting diode _D2 . However, in the conventional rapid automatic charging device shown in FIG. 1, the automatic charging control circuits 2 and 3 work in the region between t ₁ and t ₂ where the charging current I of the charging pattern shown in FIG. 2 gradually decreases. Since the voltage drop across resistor R ₁ gradually decreases, not only does the amount of light emitted by light emitting diode D ₂ decrease;
Between the charging current gradually decreasing regions _t1 and _t2, it is difficult to determine whether the light emitting diode _D2 is lit or not, and it is impossible to arbitrarily set the light-off point due to the circuit configuration. There was no indication that charging was complete. There is also a resistance in the main charging circuit.
Since this is a configuration in which R ₁ is inserted, the resistance R ₁ is inevitably inserted.
A voltage drop occurs. Therefore, in the conventional rapid automatic charging device shown in FIG. 1, it is necessary to increase the output voltage of the power rectifier circuit 1 by taking this voltage drop into account, and as a result, the power rectifier circuit 1 becomes larger. It also had a drawback.

Furthermore, in another conventional example shown in FIG.
The anode side of diode D ₁ of the charging main circuit, which has the same function as the conventional example shown in the figure, is connected to the base of transistor Q ₁ via resistor R ₃ , and the emitter of transistor Q ₁ is connected to the cathode of diode D ₁ . Connected. Further, the light emitting diode _D2 is connected in series with the resistor _R4 to the positive side of the power supply rectifier circuit 1, and is also connected to the collector of the transistor _Q1 . That is, when the charging current I flows into the main charging circuit, a forward voltage drop _VF occurs across the diode _D1 . Only when this forward voltage drop V _F is higher than the base-emitter voltage of transistor Q ₁ , the base current and collector current of transistor Q ₁ flow and light-emitting diode D ₂ lights up. However, in the conventional example shown in FIG. 3 as well, the forward voltage of the diode D ₁ increases between regions t ₁ and t ₂ where the charging current I gradually decreases after t ₁ , as in the conventional example shown in FIG. As the voltage gradually decreases, the base current and collector current of the transistor _Q1 also decrease, and when the voltage becomes equal to the base-emitter voltage of the transistor _Q1 , the transistor _Q1 is turned off. In this case, the light emitting diode D ₂
The area up to the first t ₁ is bright, and after t ₁ it gradually becomes dark, and at a certain point between t ₁ and t ₂ , the light goes out like the conventional example shown in Fig. 1, but at the time of turning off, at least the charging t ₂ at the end of charging when the current I completes its gradual decrease
(P ₁ ) point, nor is it the P ₂ point near the t ₂ (P ₁ ) point. Therefore, it is unclear at what point this light-emitting diode D ₂ turned off, and it can be determined that the light-emitting diode D 2 turned off at an arbitrary point. For example, it is not possible to set a light-off point at the _P1 point and _P2 point, and therefore this has a significant drawback as an indication of the completion of charging.

Purpose of the Invention In view of the above-mentioned drawbacks of the conventional art, the present invention provides _a point P that is arbitrarily set within a region where the charging current gradually decreases.
P The purpose is to make it possible to clearly indicate the completion of charging by turning off or turning on the light emitting diode at _two points.

Structure of the Invention In order to achieve the above object, the present invention includes a main circuit including a secondary battery to be charged and a main transistor connected in series to both ends of a power rectifier circuit, and a main transistor connected in parallel to the main circuit. The battery includes a voltage detection circuit that detects the voltage of the secondary battery, and a drive circuit that starts operation based on an output signal of the voltage detection circuit and controls the main transistor to gradually reduce the charging current to a minute current or less. Several resistors are connected in series between the other end of a resistor whose one end is connected to the base of the main transistor and the emitter of the main transistor to divide the gradually decreasing voltage at any time when the charging current gradually decreases, and this dividing voltage is connected in series. connecting the base of the transistor to the connection point of the resistor, operating the transistor at the divided voltage, and
A light-emitting diode connected to the collector side of the transistor is turned off or turned on, and the light-emitting diode remains turned on or off while the secondary battery is being charged, and is turned off or turned on at an arbitrary set point where the charging current gradually decreases. It is configured like this,
According to this configuration, the light emitting diode will gradually become darker at any point in the charging current gradually decreasing region, which is when the secondary battery is 100% charged or when the charging of the secondary battery is almost completed. It has the excellent feature that the completion of charging can be clearly indicated because the light-emitting diode turns off or lights up.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 4, 1 is a power rectifier circuit that rectifies and smoothes an AC power source (not shown), B is a secondary battery to be charged, and this secondary battery B is, for example, a Ni-Cd battery or a lead-acid battery. . 2
is a voltage detection circuit that detects the voltage of secondary battery B, 3
is an output terminal of the voltage detection circuit 2. Further, a secondary battery B, a diode D ₁ and a main transistor Q ₁ are connected in series between the positive and negative terminals of the power supply rectifier circuit 1, and the output terminal 3 of the voltage detection circuit 2 is connected to one end of a resistor R ₁ and a diode. The resistor R 1 is connected to the connection point with the anode side of D ₂ , and the other end of the resistor R ₁ is connected to the positive side of the power rectifier circuit 1 . Further, the cathode side of the diode D ₂ is connected to the gate of the field effect transistor Q ₂ , and one side of a parallel circuit consisting of a capacitor C and a resistor R ₂ is connected to the connection point between the diode D ₂ and the field effect transistor Q ₂ . However, the other side of the parallel circuit is connected to the negative side of the power rectifier circuit 1. Further, the drain of the field effect transistor Q ₂ is connected to the positive side of the power rectifier circuit 1, and the source is connected to the base of the transistor Q ₃ via a resistor R ₃ , and the collector of the transistor Q ₃ is connected to the power rectifier circuit 1. and the emitter is connected to the base of the main transistor _Q1 through a resistor _R4 ,
Furthermore, a resistor _R5 is connected between the emitter and collector of the main transistor _Q1 . At the same time, voltage dividing resistors R ₆ and R ₇ are connected in series to the emitter of the transistor Q ₃ , and the other side of the resistor R ₇ is connected to the negative side of the power rectifier circuit 1, and voltage dividing resistors R ₆ ,
The base of transistor _Q4 is connected to the connection point of _R7 . Also, this transistor _Q4 has its emitter connected to the negative side of the power rectifier circuit 1, and its collector connected to the cathode of the light emitting diode _D3 .
The anode of the light emitting diode _D3 is connected to the positive side of the power rectifier circuit 1 via a resistor _R8 . In addition, in this Figure 4, 4 surrounded by a dotted line
is an automatic charging control circuit.

The operation of the circuit configuration shown in FIG. 4 will be explained with reference to FIG. 2. As shown in FIG. 2, when the voltage V of the secondary battery B is below the set voltage of the voltage detection circuit 2, that is, the voltage V ₁ point at which the internal pressure of the battery starts to rise significantly, the output terminal 3 of the voltage detection circuit 2 Since the potential of is the same as the voltage of secondary battery B, capacitor C is connected to resistor R ₁ and diode D ₂
charged through and field effect transistor
Q ₂ , transistor Q ₃ and main transistor Q ₁ are all turned on and charging of secondary battery B is started. When charging of the secondary battery B progresses and the battery voltage V reaches the set voltage _V1 or higher of the voltage detection circuit 2, the potential of the output terminal 3 of the voltage detection circuit 2 decreases to near zero. As a result, the potential of diode _D2 is also lower on the anode side than on the cathode side, so
Charging current no longer flows through capacitor C. Therefore, the gate potential of the field effect transistor _Q2, which is equal to the voltage across the capacitor C, gradually decreases, and the source potential of the field effect transistor _Q2 also decreases, so the base potential of the transistor _Q3 decreases, and This transistor _Q3 becomes unsaturated rather than saturated. As a result, the output current of the transistor Q ₃ , the base current of the main transistor Q ₁ , and the potential between the emitter of the transistor Q ₃ and the negative side of the power rectifier circuit 1 gradually decrease, and as a result, the main transistor Q ₁ also saturates. Since the state becomes an unsaturated state, the charging current I starts to gradually decrease from the point _t1 , as shown in FIG. When the discharge of the capacitor C progresses and the gate potential of the field effect transistor Q ₂ becomes zero, the field effect transistor Q ₂ and the transistor Q ₃ are turned off.
The main transistor Q ₁ is also turned off, and charging of the secondary battery B is completed at point t ₂ (P ₁ ). After the charging current I has gradually decreased, that is, after the point _t2 , an auxiliary charging current is caused to flow through the secondary battery B through a resistor _R5 connected in parallel between the collector and emitter of the main transistor _Q1 .

According to the charging pattern shown in Figure 2, approximately 80% of the battery capacity is charged up to point t ₁ , and between t ₁ and t ₂ when the charging current I gradually decreases, the internal pressure of the secondary battery B decreases. It completes 100% charging while suppressing the rise, and at point t ₂ (P ₁ ) or its nearby point P ₂ ,
If the completion of charging is indicated by the light emitting diode _D3 , the battery can be charged to almost 100%. Hereinafter, the charging completion display operation will be explained in detail with reference to the circuit configuration shown in FIG. 4. The charging current I in Fig. 2 gradually decreases.
Between t ₁ and t ₂ , at the same time as the transistor Q ₃ shifts from the saturated state to the unsaturated state, the potential between the emitter of the transistor Q ₃ and the negative side of the power supply rectifier circuit 1 starts to gradually decrease, and the capacitor As the discharge of C proceeds further, the charging current I reaches the point P ₁ at time t ₂ . At this t ₂ (P ₁ ) point,
Resistors R ₆ and R ₇ divide the potential between the emitter of transistor Q ₃ and the negative side of power rectifier circuit 1.
Therefore, if the resistance value at which the transistor Q ₄ is turned off is appropriately set, the light emitting diode D ₃ is turned off.
That is, between t ₁ and t ₂ from the initial stage of charging, the voltage dividing resistors R ₆ and R ₇ are connected to the resistor R ₇ and the transistor Q ₄
Since the connection point potential of the base of is higher than the base-emitter voltage for turning on the transistor _Q4 , the base current of the transistor _Q4 flows through the resistor _R6 . As a result, the transistor _Q4 is turned on and becomes saturated, so that current flows to the light emitting diode _D3 via the resistor _R8 , and the light emitting diode _D3 remains lit. At time _t2 , when the discharge of the capacitor C further progresses and the potential between the emitter of the transistor _Q3 and the negative side of the power supply rectifier circuit 1 approaches zero V, as explained above, the transistor _Q4 turns off. Since the conditions, that is, the resistance values of the voltage dividing resistors R ₆ and R ₇ are set appropriately, the base current does not flow to the transistor Q ₄ ,
As a result, transistor _Q4 is turned off. As a result, the light emitting diode D ₃ connected in series with this transistor Q ₄ turns off, and thereafter remains in the off state. In this way, one embodiment of the present invention solves the problem of the conventional example shown in FIGS. 1 and 3, namely, the problem that the light emitting diode cannot be turned off at an arbitrary set point where the charging current gradually decreases. This is the solution.

FIG. 5 shows another embodiment of the present invention,
The embodiment shown in FIG _. 5 also turns off the light emitting diode at an arbitrary set point, similar to the embodiment shown in FIG. 5, only the points different from the embodiment shown in FIG. 4 will be explained below in FIG. 5. That is, in FIG. 5, the collector of transistor Q ₄ is connected to the positive side of power rectifier circuit 1 via resistor R ₈ , and the emitter is connected to the negative side of power rectifier circuit 1 . and connect the base of another transistor _Q5 to the connection point between the resistor _R8 and the collector of the transistor _Q4 ,
The collector of this transistor Q ₅ is connected to the positive side of the power rectifier circuit 1 via a resistor R ₉ , and the emitter of this transistor Q ₅ is connected to the negative side of the power rectifier circuit 1 . Furthermore, the anode side of the light emitting diode _D6 is connected to the other transistor.
It is connected to the collector of Q ₅ , and the cathode side is connected to the negative side of the power rectifier circuit 1. Also in the embodiment shown in FIG. 5, the transistor Q ₄
As in the embodiment shown in FIG. 4, it is turned on from the beginning of charging and reaches a saturated state. In this case, the base-emitter potential of another transistor _Q5 becomes the collector-emitter voltage of transistor _Q4 , so
The base-emitter voltage necessary to turn on another transistor _Q5 is not available, and as a result, another transistor _Q5 turns off. As a result, a current flows through the light emitting diode _D6 via the resistor _R9 , causing the light emitting diode _D6 to light up and maintain its lighted state. Furthermore, at time t ₂ when transistor Q ₄ is turned off in the charging current gradually decreasing region, that is, at an arbitrary set point between t ₁ and t ₂ shown in FIG. 2, another transistor Q ₅ is connected to the base via resistor R ₈ As the current flows, a collector current also flows through the resistor R ₉ , so this other transistor Q ₅ is instantly turned on and becomes saturated. i.e. another transistor
It is connected between the collector and emitter of _Q5 . From the forward voltage required to light the light emitting diode _D6 ,
Generally, the collector-emitter saturation voltage of another transistor _Q5 is sufficiently low, so the current flowing through the light emitting diode _D6 is transferred to another transistor _Q5 .
is bypassed between the collector and emitter of the light emitting diode D6, and the light emitting diode _D6 turns off instantaneously and thereafter remains in the off state, resulting in a display mode of the light emitting diode similar to the embodiment of the present invention shown in FIG. It has the following. In the embodiment of the present invention shown in FIG. 4, the transistor _Q4 is driven by a gradually decreasing voltage between the emitter of the transistor _Q3 and the negative side of the power supply rectifier circuit 1. The collector current of transistor _Q4 also decreases as the base current of transistor _Q4 decreases, so the turn-off point of light-emitting diode _D3 can be set arbitrarily, but the light-emitting diode _D3 connected in series with transistor _Q4 The amount of light emitted varies between t ₁ and t ₂ when the charging current gradually decreases. However, in the embodiment shown in FIG. 5, the light emitting diode D6 operates only when the transistor _Q4 turns on and off, and another transistor _Q5 turns off and on, causing the light emitting diode _D6 to operate. The current flowing through D ₆ is the resistance R ₉
Determined by Therefore, even in the region between t ₁ and t ₂ where the charging current gradually decreases, the light emitting diode D ₆ can be lit stably without fluctuation in the amount of light emitted.
Furthermore, if a diode is connected in the forward direction between the collector of transistor Q ₄ and the base of another transistor Q ₅ in Fig. 5, the switching operation of another transistor Q ₅ can be made more reliable. be.

FIG. 6 shows yet another embodiment of the present invention, in which polarity is established between the collector of another transistor Q ₅ and the resistor R ₉ shown in FIG. In this embodiment, the light emitting diode D ₇ is turned off while the secondary battery B is being charged, and the light emitting diode D ₇ is turned off at any point where the charging current gradually decreases.
D ₇ lights up and stays lit.

FIG _. 7 shows another embodiment of the present invention. In the embodiment shown in FIG _. A light emitting diode _D8 is connected between the collector and the negative side of the power rectifier circuit 1. In the embodiment shown in FIG. 7, the secondary battery B During charging, the light emitting diode D ₈ goes out, and at any point where the charging current gradually decreases, the light emitting diode D 8 turns off.
_D8 lights up and stays lit.

Effects of the Invention As described above, according to the present invention, 100% of the secondary battery
% charge or at any point in the charging current gradual reduction region when charging of the secondary battery is almost completed, the light emitting diode turns off or lights up instead of gradually dimming as in the conventional case. It has an excellent feature of being able to clearly display the completion of charging.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of a conventional automatic charging device, Fig. 2 is a charging characteristic diagram of the same charging device, Fig. 3 is an electric circuit diagram of an automatic charging device showing another conventional example, Fig. 4,
FIG. 5, FIG. 6, and FIG. 7 are electrical circuit diagrams of automatic charging devices showing respective embodiments of the present invention. B... Secondary battery, 1... Power rectifier circuit, 2... Voltage detection circuit, 4... Automatic charging control circuit, Q 1... Main transistor, Q ₂ ... Field effect transistor, Q _{3 ,} Q ₄ ,
_Q5 ...transistor, _D1 , _D2 ...diode, _D3 ,
D ₄ , D ₅ , D ₆ , D ₇ , D ₈ ... Light emitting diode, C ... Capacitor, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₈ , R ₉ ... Resistor, R ₆ , R ₇ ...Divisional voltage resistance.

Claims (1)

[Claims] 1. A main circuit formed by connecting a secondary battery to be charged and a main transistor in series to both ends of a power rectifier circuit, and a voltage detection circuit connected in parallel to this main circuit and detecting the voltage of the secondary battery. , a drive circuit that starts operating in response to the output signal of the voltage detection circuit and controls the main transistor to gradually reduce the charging current to a minute current or less, the other end of the resistor having one end connected to the base of the main transistor. and the emitter of the main transistor, connect several resistors in series that divide the gradually decreasing voltage at arbitrary times when the charging current gradually decreases, and connect the base of the transistor to the connection point of the divided resistors, The transistor is operated with the divided voltage gradually decreasing, and a light emitting diode connected to the collector side of the transistor is turned off or turned on, and the light emitting diode is kept turned on or turned off while the secondary battery is being charged; An automatic charging device configured to turn off or turn on at an arbitrary set point where the charging current gradually decreases.