JPH02285936A - Charging circuit - Google Patents

Abstract

PURPOSE:To display the state of charging accurately, and to simplify constitution by providing a display circuit displaying the state of charging of a secondary battery controlled by an output ON-OFF controlling the switching element of a charging control circuit. CONSTITUTION:Since a light-emitting diode LD blinks when a secondary battery B is charged normally and a transistor Q2 is left as it is brought to an ON state when the secondary battery B is not connected, when the internal resistance of the secondary battery is increased by the lifetime of the battery, etc., and charging currents do not reach a fixed value or the like, a transistor Q3 is turned OFF, and the light-emitting diode LD is kept under the state of putting off at that time, thus allowing the display of no-normal charging. Accordingly, when the transistor Q3 is ON-OFF controlled by the transistor Q2, the lighting of the light emitting diode LD can be controlled in response to the state of operation of a charging control circuit 1, a display circuit 7 is not operated independent of the operation of the circuit 1, and no comparator for discriminating normality or abnormality is required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charging circuit that charges a secondary battery and includes a display circuit that displays the state of charge of the secondary battery.

[Prior Art] Fig. 3 shows a conventional charging circuit. This charging circuit uses, as a charging power source, a DC power source obtained by step-down rectifying a commercial power source AC using a transformer T and a rectifier Re. In this charging circuit, a transistor Q is connected between this power source and the secondary battery B.
A charging control circuit 1 detects the charging current and controls the on/off state of the transistor Q to keep the charging current constant. Here, the charging control circuit 1 detects the charging current from the voltage generated across the resistor R inserted in series with the secondary battery B, and detects the charging current from the voltage generated across the resistor R inserted in series with the secondary battery B.
, to control on/off. Specifically, the voltage generated across the resistor R1 is applied to the operational amplifier OP.
1 and resistors R2 to R5, and outputs a voltage corresponding to the charging current (instantaneous value). Then, the output of this differential amplifier circuit 2 is integrated by an integrating circuit 3 consisting of a resistor R5 and a capacitor C2, and the operational amplifier OP,
The output of the non-inverting amplifier circuit 4 is further integrated by an integrating circuit 5 consisting of a resistor R and a capacitor C1, and then an operational amplifier OP3 and a zener Comparison is made by a comparator 6 consisting of a diode ZD and a resistor R3°. Here, if the output of the integrating circuit 5 is lower than the reference voltage Vref created by the Zener diode ZD, the output of the comparator 6 becomes high level, turning on the transistor Q2 and turning on the transistor Q. . In this way, transistor Q
When , is turned on, charging current is supplied to secondary battery B.

Further, if the output of the integrating circuit 5 is higher than the reference voltage Vref, the output of the comparator 6 becomes a low level, and the transistor Q2 is turned off, so that the transistor Q1 is controlled to be turned off, and the charging of the secondary battery B is Current supply is stopped. Note that the diode D2 connected in series to the secondary battery B is a diode for regulating the current direction, and the 21E source of the control circuit 1 and the display circuit 7 described below connects the output of the rectifier Re to the diode D and It is obtained by rectification and smoothing by a control power supply circuit 12 consisting of a capacitor C1.

This charging circuit includes a display circuit 7 that displays the charging state of the secondary battery B. In other words, this display circuit 7 connects the output of the integrating circuit 5 to the operational amplifier OP, Zener diode ZD.
, and a resistor R21. When the output of the integrating circuit 5 is higher than the reference voltage Vref2, the output of the comparator 8 becomes high level, and the output of the comparator 8 drives the transistor Q. When turned on, the light emitting diode LD lights up, thereby indicating that the charging current is equal to or higher than a predetermined value and charging is being performed normally.

Problem 1 to be Solved by the Invention E However, in the display circuit 7 of this conventional charging circuit, since the comparator 8 determines whether or not the charging state is normal, the configuration becomes complicated, and the comparator 8 Depending on the setting conditions of the reference voltage, it is possible that the charging control circuit j operates independently of the operation of the charging control circuit j, which is not preferable.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a charging circuit that accurately displays the state of charge and has a simple configuration.

[How to solve the problem Fi1 To achieve the above object, the present invention includes a switch element connected between a charging power source and a secondary battery, and a switch element that detects a charging current and turns the switch element on and off. The battery includes a charging control circuit that controls the charging current to be constant, and a display circuit that is controlled by an output that turns on and off a switch element of the charging control circuit and displays the state of charge of the secondary battery.

[Operation 1] The present invention controls the display circuit with an output that turns on and off the switch elements of the charge control circuit as described above, so that the display circuit charges the secondary battery according to the operating state of the charge control circuit. In addition to being able to display the status, charging
By using the output of the li control circuit that indicates the state of charge in the display circuit, there is no need for the display circuit to determine whether or not the state of charge is normal, which simplifies the configuration of the display circuit. be.

[Embodiment 11] Fig. 1 shows an embodiment of the present invention. In this embodiment, a resistor RI is connected to a transistor Q3 that lights up a light emitting diode LD.
A base current is supplied from the control power supply circuit 12 via 2 and diodes D and 4, and a diode D is connected to the connection 5α between the resistor R+z and the diode D and the collector of the transistor Q2. Note that the other configurations are the same as the conventional circuit.

In this embodiment, the transistor Q2 of the charging control circuit 1 is turned on when the charging current is smaller than a predetermined current value;
The transistor Q is turned on and off in a reciprocal manner depending on the off state. In other words, transistor Q2
is on and charging current is being supplied to the secondary battery B via the transistor Q■, the transistor Q3 is turned off and the light emitting diode LD is turned off, and the transistor Q2 is turned off and the charging current is supplied to the secondary battery B. When the supply of charging current to the battery B is stopped, the transistor Q is turned on to light up the light emitting diode LD.In other words, when the secondary battery B is being charged normally, the light emitting diode LD is turned on.
should be blinking.

Furthermore, if the secondary battery B is not connected, or if the internal resistance of the secondary battery increases due to battery life etc. and the predetermined charging current is not reached, the transistor Q2 remains in the on state. Therefore, the transistor Q is turned off, and at this time, the light emitting diode LD is kept in the off state, so that it can be indicated that the battery is not being charged normally. By controlling the transistor Q3 on and off using the transistor Q2 in this way, it is possible to control the lighting of the light emitting diode LD according to the operating state of the charging control circuit 1. Therefore, the display circuit 7 can control the operation of the charging control circuit 1. It does not work independently of the . Moreover, since the display circuit 7 does not require a comparator for determining whether or not it is in a normal charging state,
The circuit configuration also becomes simpler.

[Example 21 Figure v42 shows another example of the present invention. This embodiment is a charging circuit for a secondary battery B that turns on an emergency light in an emergency. In the display circuit 7 of this charging circuit, a light emitting diode LD is connected to the output of the control power supply circuit 12, and a transistor Q3 is connected to both ends of the light emitting diode LD! l continued,
The on/off state of this transistor Q is controlled by the output of the comparator 6 via a resistor R12 and a diode D4.

In other words, in this display circuit 7, when the charging current is thicker than a predetermined value (i.e., when the output of the comparator 6 is at a low level, the transistor Q is turned off, lights up the light emitting diode LD, and also charges If the current is smaller than the predetermined value, comparator 6
When the output of ) is at a high level, the lannostar Q3 is turned on and the light emitting diode LD is turned off.

In this charging circuit, the lighting control circuit 9 keeps the incandescent light off when the commercial power supply AC is supplied, and turns on the incandescent light using the secondary battery B when the supply of the commercial power supply AC is stopped. It is equipped with In this lighting control circuit 9, a comparator 10 consisting of an operational amplifier OP and resistors R1 to R4 divides the reference voltage Vref created by a Zener diode ZD and the output of the control power supply circuit 12 by resistors R13 and R1. Commercial power AC
This is to detect the supply status. In other words, while commercial power AC is being supplied, the voltage divided by the resistors R+s and R is set to be higher than the reference voltage Vref+, so the output of the comparator 10 turns on and off. When the transistor Q6 is turned on, the transistor Q that connects the incandescent lamp to the secondary battery B is turned off, and the incandescent lamp is kept in an extinguished state. When the supply of commercial power AC is stopped due to a power outage, etc., the resistance R
, , R, , is lower than the reference voltage Vref, so the output of the comparator circuit 10 becomes low level,
When the transistor Q6 is turned off, the transistor Q is turned on, and the incandescent lamp is turned on by the secondary battery B.

Here, in the display circuit 7, when the incandescent lamp is disconnected or not connected, the comparator 6 of the charging control circuit 1
Regardless of the output state of the light emitting diode LD, the light emitting diode LD can be turned off to indicate a disconnection or the like. For this reason, a series circuit of a resistor RI7 and a diode D is connected between the output of the control power supply circuit 12 and the base of the transistor Q, and a series circuit of a resistor R17 and a diode D is connected between the connection point of the resistor R17 and the diode D and the ground. A transistor Q4 is connected, and this transistor Q4 is turned on and off depending on the connection of the incandescent light.6 In other words, if a disconnection occurs in the incandescent light,
When transistor Q4 is turned off, a base current is supplied to the base of transistor Q through resistor R+ and diode D, and transistor Q3 is turned on.
The light emitting diode LD is kept in an off state regardless of the output of the comparator 6. Therefore, in the display circuit 7 of this embodiment, the light emitting diode LD lights only when the commercial power supply AC is energized, charging is completed normally, and the incandescent light is normally connected. Become.

In this way, since the connection state of the incandescent light can also be detected, safety as an emergency light can be ensured. Note that the resistor R18, which is connected between the base of the transistor Q and the ground, and the resistor RIB, which is connected to both ends of the transistor Q, are pull-down resistors to stabilize the circuit operation, and are set to a high resistance value. I'm doing it.

[Effect of the Invention 1] As described above, the present invention is controlled by the output that controls the switching elements of the charging control circuit on and off, and is equipped with a display circuit that displays the charging state of the secondary battery. The charging state of the secondary battery can be displayed on the display circuit according to the operating state of the charging control circuit, so that the display circuit does not operate independently of the operation of the charging control circuit. Moreover, since the display circuit uses the output from the charging control circuit that indicates the charging state, there is no need for a comparator in the display circuit to determine whether or not the charging state is normal, which simplifies the configuration of the display circuit. can do.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is a circuit diagram of another embodiment, and FIG. 3 is a circuit diagram of a conventional example. 1 is a charging control circuit, 7 is a display circuit, Ql is a transistor, and B is a secondary battery. Agent Patent Attorney Ishi 1) Ai Shichi

Claims (1)

[Claims] (1) A switch element connected between a charging power source and a secondary battery, and a switch element that detects the charging current and turns on the switch element.
A charging circuit that includes a charging control circuit that controls the charging current to a constant level by controlling off, and a display circuit that is controlled by an output that controls on and off a switch element of the charging control circuit and displays the state of charge of a secondary battery. .