JPS64896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overdischarge prevention device for storage batteries used in electronic equipment.

Traditionally, electrical equipment that uses storage batteries requires a switch.
If you leave the battery in the ON state and allow it to completely discharge, it will often damage the battery and make it impossible to charge it. For this reason, it has been considered to issue an alarm when the battery voltage drops, but since the battery voltage has already dropped at this point, it is not only impossible to send out an alarm at a loud volume for a long time.
If no one turns off the switch, it will further drain the battery.

If the storage battery is discharged in this way, it will no longer be able to be charged with the charger.

The present invention eliminates these drawbacks, and even if you forget to turn off the switch, the current supply to the load is cut off before the battery is completely discharged, and the battery can be discharged in a state where the battery function can be restored by an ordinary replenishment charger. The present invention provides an overdischarge prevention device having a function of preventing extreme battery consumption by terminating the overdischarge.

FIG. 1 shows how to use the over-discharge preventer of the present invention, in which A is a built-in battery, C is a wireless communication device serving as a load, and over-discharge preventer B is connected between them.

Fig. 2 shows an overdischarge prevention device according to an embodiment of the present invention. 1 is a built-in battery, TC is a charging terminal, and 4 is a power switch consisting of switches S ₁ and S ₂ that are interlocked with each other, and when S ₁ is OFF. S ₂ is ON, and when S ₁ is ON, S ₂ is OFF. Q ₁ is the main switch transistor, Q ₂ is a control transistor that helps the operation of transistor Q ₁ , and Q ₃ is transistor Q _2.
An inhibiting transistor that controls the operation of R ₂ ,
R ₃ is a resistor, C ₁ is a large capacitor, R ₄
is a resistor for discharging the charge of capacitor _C1 , and is connected to one fixed contact of switch _S2 via terminal 5, so that it is grounded when switch _S1 is OFF. Z ₁ is the first Zener diode, U ₁ is the voltage comparator, R ₈ ,
R ₉ and R ₁₀ are resistors connected in series, and the movable terminal of variable resistor R ₉ is connected to the + terminal of voltage comparator U ₁ . R ₇ is a resistor connected in series with the second Zener diode Z ₂ . C ₂ is a noise bypass capacitor. Transistor for main switch
The collector of Q ₁ is connected to the radio C via the output terminal T ₀ to supply power to the radio C.

Next, the operation will be explained.

Assume now that the terminal voltage of the built-in storage battery 1 is _VB , and that the charge in the capacitor _C1 is being discharged via the switch _S2 as shown in the figure. When power switch S ₁ is turned ON, switch S ₂ is turned OFF, power is supplied from built-in battery 1 to transistor Q ₁ , and due to the operation of transistor Q ₂ , output voltage V ₀ is output to output terminal T ₀ , which is applied to the load. The signal is supplied to the wireless device C. At this time, the voltage at terminal T ₀ is
V ₀ =(V _B −IR _b −IR _q1 ).

Here, R _b is the internal resistance of the battery, and R _q1 is the internal resistance of transistor Q ₁ .

V _B and R _b change depending on the state of battery charging and discharging.
Moreover, R _q1 changes depending on the operating state of Q ₁ . Therefore,
A voltage [V _B −I (R _b +R _q1 )] is supplied to the wireless communication device C, and this voltage is applied as a voltage V ₁ to the voltage comparator U ₁ through resistors R ₈ and R ₉ . If the ground side resistance of variable resistor R ₉ is R′ ₉ , then V ₁
is ((R' ₉ + R ₁₀ )/(R ₈ + R ₉ + R ₁₀ )), and compared with the terminal voltage V _Z2 of Zener diode Z ₂ , V ₁
>V _Z1 , transistors Q ₂ and O ₃ are operated, transistor Q ₁ is made conductive, and power continues to be supplied from built-in battery 1 to wireless communication device 3.

Now, as the battery wears down during use, the voltages V _B and V ₀ gradually decrease, and when they fall below the preset usage limit, V ₃ < V _Z1 , and the transistor Q ₃
OFF, capacitor C ₁ is connected to transistor Q ₁ +
It is sequentially charged with the current from Q ₂ and eventually reaches a value close to V _B. Therefore, transistors Q ₂ and Q ₁ are turned off, and V ₀ ≈0 (V). Radio device C as a load
As the current to becomes 0, _VB gradually recovers its voltage, but since transistor _Q1 is not operated again, battery consumption is automatically stopped, and even if you forget to turn off the power switch, It will not over discharge the battery.

However, when I turned off the power switch _S1 and turned it on again
If the battery voltage has recovered to above the operating limit value, output will be obtained again at the output terminal _T0 , and the radio
can be operated for only a short period of time.

When this is used in a press-talk type radio device, the circuit configuration is as shown in FIG. 3. power switch
By turning on _S1 , power is applied directly from battery 1 to overdischarge prevention circuit B and transmitter _TX of radio device C. On the other hand, the receiver R _X receives power from the overdischarge prevention circuit B and operates. The transmitter T _X operates when the press talk switch S _T attached to the microphone is pressed down, and sends operation information I _C to the receiver R _X to stop its operation. S _A is the antenna switching switch, which switches the antenna (ANT) to the transmitter T _X side when the pre-talk switch S _T is ON. At this time, when the press switch is turned on, the reference voltage V _Z2 of the over-discharge prevention circuit B is configured to be grounded from _two Zener diodes Z through a resistor R ₁₂ and a diode D ₁ . Voltage
It is recommended to use this together with lowering V _Z2 .

The switch that supplies power to the load was explained using a transistor switch as an example, but as shown in Fig. 4, a relay R _y is used instead of Q ₁ , and the current is controlled by a transistor Q ₂ , and the contact of the relay R _y is The load may be powered by S _r .

As explained above, the battery overdischarge prevention device of the present invention detects the output voltage and controls the switch transistor, and can cut off the current supply to the load before the battery is completely discharged. Furthermore, when the power switch is turned off, the voltage of the capacitor is discharged to return to the initial condition, so there is no need to provide a clear circuit, making it easy to use and operate in electronic equipment.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the state of use of the charge/discharge control device of the present invention, Fig. 2 is a wiring diagram of an overdischarge prevention device according to an embodiment of the present invention, and Fig. 3 is an application to a presstalk type wireless device. A block diagram showing an example, FIG. 4 is a partial electrical wiring diagram of an example in which a relay is used in the main switch circuit. U ₁ ... Voltage comparator, Q ₁ , Q ₂ , Q ₃ ... Transistor, S ₁ , S ₂ ... Switch, C ₁ ... Capacitor.

Claims (1)

[Claims] 1 a first switch that turns on and off the output of the storage battery; a first current control means that receives the output of the first switch as an input and whose output is connected to a load;
a second current control means that compares the voltage supplied to the load with a reference voltage, and is in an ON state when the output voltage of the storage battery is equal to or higher than a termination voltage, and is turned OFF when it is equal to or lower than the termination voltage; a capacitor inserted between the means and the control terminal of the first current control means and the ground, the capacitor being connected between the capacitor and the ground, interlocking with the first switch; An overdischarge prevention device comprising a second switch that forms a discharge circuit for the capacitor when the switch is ON, and cuts off the discharge circuit when the first switch is OFF.