JPS622545Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a battery checker for emergency lights that indicates over-discharge when the voltage of a secondary battery that serves as an emergency power source for emergency lights, guide lights, etc. falls below a certain specified voltage. It is something.

The conventional battery checker for emergency lights is
As shown in the figure, a current limiting resistor _R9 is connected to the output of an AC power source that has been step-down rectified by a transformer T and a rectifier D to form a charging power supply circuit that charges a secondary battery B. A battery voltage detection circuit is connected between B and B, and this battery voltage detection circuit is configured as follows. That is, both ends of the secondary battery B are divided by resistors R ₁ and R ₂ , and the divided resistors R ₁ and R _2
The base _of the first transistor _Q1 of NPN type is connected to the midpoint _of The emitter of the second transistor Q2 is connected to the base of the second PNP transistor _Q2 through the resistor _R5 , and the emitter of the second transistor _Q2 is connected to the negative side of the secondary battery B through the resistor _R6 . Connect to the positive side of secondary battery B,
The collector is connected to the negative side of the secondary battery B via a resistor _R7 , and between the emitter of the second transistor _Q2 and the emitter of the first transistor _Q1.
A PNP type third transistor _Q3 is connected, and a display element LED made of a light emitting diode is connected between the emitter of the third transistor _Q3 and _the emitter of the second transistor _Q2 . The base is connected to the collector of the second transistor Q ₂ through a resistor R ₈ , and the third
Connect the collector of transistor Q ₃ to the first transistor
It was constructed by connecting to the emitter of _Q1 .

In the battery checker with the above configuration, when the AC power supply is turned on, the secondary battery B is charged with a small current that does not pose the risk of overcharging, and in the event of a power outage, the power outage detection switch SW is turned on, and the lamp L is an emergency power source. Lights up using secondary battery B. When the voltage of the secondary battery B drops below a certain specified voltage due to the lighting of the lamp L, the battery voltage detection circuit operates to light the display element LED. Note that the lighting voltage of the display element LED is determined by the dividing value of the dividing resistors R ₁ and R ₂ when the first transistor Q ₁ is turned from on to off. The basic operation of the battery voltage detection circuit is that during normal operation when the voltage of the secondary battery B is high, the first
The transistor Q ₁ is on, the second transistor Q ₂ is on, the third transistor Q ₃ is off, and the display element LED is off. Lamp L due to power outage
lights up and when the voltage of secondary battery B drops below a certain specified voltage, the first transistor Q ₁ turns off, the second transistor Q ₂ turns off, and the third transistor Q ₃ turns on, and the display element LED lights up. do. If secondary battery B is disconnected for some reason, a pulsating DC voltage will be applied to the battery voltage detection circuit, and as a result, only the conduction width where the first transistor Q ₁ is off will be applied. , the third transistor _Q3 is turned on, so the display element
The LED lights up to indicate that there is an abnormality in which the secondary battery is disconnected, and functions as a battery checker.

However, with only the above circuit configuration, when fluctuations in the AC power supply occur, the charging current changes in the charging power supply circuit, resulting in problems such as overcharging and undercharging. Therefore, in view of the need for constant current charging without being affected by such fluctuations in the AC power source, the configuration of the charging power source shown in FIG. 2 has been considered. That is, in order to reduce power loss in the components when configuring a constant current charging circuit, a smoothing capacitor C is connected to the output of the charging power supply circuit shown in FIG. 1, and a constant voltage diode Z _D , When a constant current circuit consisting of a current compensation resistor R _Z , an NPN type transistor Q, and an emitter resistor Re is connected, if the secondary battery B becomes disconnected, the current from the charging power supply circuit will be as shown in Figure 1. Since the load is only the voltage detection current flowing through the battery voltage detection circuit shown in the diagram, the output voltage from the charging power supply circuit instantly becomes a smooth high voltage with no pulsation. The output voltage of the transformer T becomes high, and as a result, the first transistor Q ₁ turns on, so the second
Transistor Q ₂ is turned on, third transistor Q ₃ is turned off, and the display element LED does not light up. When the constant current circuit is connected to the charging power supply circuit in this way, there is a problem in that an abnormality is not displayed when the secondary battery B is disconnected.

As described above, even when the constant current circuit is connected to the charging power supply circuit, the present invention can
An embodiment of the present invention will be described with reference to FIG.

Figure 3 shows an example in which a constant voltage diode _ZD is connected between the cathode of the display element LED of the battery voltage detection circuit in Figure 2 and the negative side of the secondary battery B; Z _D is connected so that the anode becomes the negative side of secondary battery B. In this circuit configuration, secondary battery B
If the battery becomes disconnected, the LED display element lights up as described below to indicate that the battery has disconnected. That is, when the secondary battery B is normally connected, the load on the charging power supply circuit is the charging current to the secondary battery B and the voltage detection current. In this case, the relationship between charging current and voltage detection current is charging current≫voltage detection current. If secondary battery B becomes disconnected, the load on the charging power supply circuit will be light, consisting only of the voltage detection current, so the output voltage of the transformer 7 that constitutes the charging power supply will be high, and the battery voltage detection The voltage applied to the circuit also increases. As a result, the voltage across the constant voltage diode Z _D increases to a voltage at which the constant voltage diode Z _D becomes conductive, and the display element LED is forcibly turned on. In this case, the constant voltage diode Z _D is not conductive when the secondary battery B is connected normally, but is conductive when the secondary battery B is disconnected.

As described above, according to the present invention, even when the constant current circuit is connected to the charging power supply circuit, if the secondary battery becomes disconnected, the cathode of the display element of the battery voltage detection circuit and the secondary battery This device has an excellent feature in that an abnormality can be displayed by operating the display element using a constant voltage diode connected between the negative side and the negative side.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram of a conventional battery checker for emergency lights, Fig. 2 is an electric circuit diagram with a constant current circuit added to Fig. 1, and Fig. 3 is an electric circuit diagram for emergency lights showing an embodiment of the present invention. It is a battery voltage detection circuit diagram of a battery checker. ...charging power supply circuit, ...battery voltage detection circuit, ...constant current circuit, R ₁ , R ₂ ...dividing resistor,
_R3 to _R8 ...Resistor, _Q1 ...First transistor, _Q2
...second transistor, Q ₃ ...third transistor, LED ...display element, Z _D ...constant voltage diode, B ...secondary battery.

Claims (1)

[Scope of utility model registration request] A smoothed charging power supply circuit, a secondary battery connected to this charging power supply circuit via a constant current circuit, and a base connected to the midpoint of a dividing resistor that divides the voltage of this secondary battery, and an emitter , a first transistor whose collector is connected to both ends of the divided resistor through a resistor, which is of a different type from this first transistor, whose base is connected to the collector of the first transistor, and whose emitter and collector are connected to both ends of the divided resistor through a resistor. and a second transistor of the same type as the second transistor, whose base is connected to the collector of the second transistor, whose emitter is connected to the emitter of the second transistor via the display element, and whose collector is connected to the emitter of the first transistor. and a battery voltage detection circuit consisting of a third transistor, which detects an abnormal voltage increase when the battery is disconnected between the cathode of the display element of the battery voltage detection circuit and the negative side of the secondary battery, and operates the display element. A battery checker for emergency lights, which is characterized by connecting a constant voltage diode.