JPS6341808Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device for preventing over-discharge of a battery in a press-to-talk type radio device or the like when the reception switch is forgotten to be turned off and during transmission.

Conventionally, with press-to-talk radio line equipment that uses a battery, forgetting to turn off the power switch can completely discharge the storage battery and make the battery unusable, or it can take a lot of effort and effort to charge it to restore performance. be. Especially when discharged with a small current, the damage is often particularly severe. That is, the final voltage of the battery changes depending on the current used, and if the final voltage at low currents is used to prevent overdischarge, there is a drawback that the battery becomes unusable even though there is still some remaining capacity.

The present invention aims to provide an overdischarge prevention device that can be applied not only to overdischarge caused by forgetting to turn off the switch during reception, but also to situations in which high current is used, such as during press talk calls. This will be explained below along with examples.

FIG. 1 shows an over-discharge prevention circuit for a storage battery of a press talk type radio device according to an embodiment of the present invention. TC is a charging terminal, B is a storage battery, _S1 is a power switch with a make contact, and _S2 is a recovery switch for canceling the overdischarge prevention condition, and this switch has a break contact that interlocks with the power switch _S1 . Q ₁ is the transistor for the first switch, Q ₂
is the transistor that controls transistor Q ₁ , Q ₃
is a transistor that controls the operation of transistor _Q2 . _Q4 is a transistor for a circuit switch that changes the operating conditions of transistor ^Q2 , and _U1 is a voltage comparator consisting of an operational amplifier.
The voltage obtained by dividing the output voltage V ₀ of Q ₁ is compared with the voltage of the Zener diode Z ₂ , and the comparison information is output to the transistor Q ₃ .

R ₁ is the protection resistance of transistor Q ₁ , R ₂ is the resistance for current limiting during reception, R ₃ is the protection resistance of transistor Q ₂ , R ₄ is the discharge resistance of capacitor C ₁ , R ₅ , R ₆
is a voltage dividing resistor, _R7 is a protective resistor, resistors _R8 , _R9 ,
_R10 constitutes a voltage divider circuit that determines the supply voltage during reception. The resistors R ₈ , R ₉ , R ₁₀ and the regulator R ₁₁ constitute a voltage divider circuit that determines the supply voltage during transmission, and the pre-talk switch S ₃ uses a transfer switch in this embodiment.
When OFF, the contacts of resistor R ₁₀ and resistor R ₁₁ are grounded to provide a comparison voltage during reception, and when press talk switch S ₃ is ON, this ground is released to provide a comparison voltage during transmission. R ₁₂ is a series resistor, C ₁ is a bias holding capacitor that inhibits the operation of transistors Q ₁ and Q ₂ , C ₂ is a capacitor for the Zener diode Z ₂ noise bypass circuit, and Z ₁ is a Tsuena diode voltage comparator. When the output of U ₁ exceeds the Zener voltage of Zener diode Z ₁ , the transistor
Make a move to turn Q ₃ ON. T ₀ is the output terminal that supplies power to the radio, and the charging terminal of battery B T _C
The final voltage V _B of the battery changes depending on the load current. This change results in a voltage change as shown in FIG. 2, for example. Therefore, for example, if the load current during reception is 0.1A, the battery terminal voltage is
If 10.5V and the load current during transmission is 1A, the voltage will be 9.5V during transmission. When using a battery,
By using this final voltage as a standard, batteries can be maintained safely and with a long lifespan. Power switch S ₁
When turned ON, switch S ₂ is turned OFF at the same time.
becomes. At this time, the voltage of the capacitor C ₁ is O, transistors Q ₁ and Q ₂ are turned on, and an output voltage V ₀ is output to the output terminal T ₀ . This voltage is applied on the one hand to the b terminal of the comparator U ₁ by a resistor R ₁₂ and a Zener diode Z ₂ which constitute an arm that determines the reference voltage, and also to resistors R ₈ , R ₁₀ , a potentiometer R ₉ and a presstalk switch S Comparator U ₁ adjusts the voltage with the volume R ₉ in the arm of ₃ and earth
In addition to the a terminal of , compare the voltage. In the case of FIG. ₁ , the dead point voltage of the comparator U1 is set at a point where _V0 is slightly below 10.5V. Therefore, a voltage approximately equal to V ₀ appears at the c terminal of the comparator U ₁ , and with respect to the Zener voltage V _Z1 of the Zener diode Z ₁ , V ₀ >
When V _Z1 , transistor Q ₃ is turned on and capacitor C ₁ is shorted, transistors Q ₁ and Q ₂ are operated to continue supplying power to the load.

Then V ₀ drops below 10.5V and comparator U ₁ turns OFF
Then, transistor Q ₃ turns OFF, and the base current of transistor Q ₂ charges capacitor C ₁ , turning transistor Q ₂ OFF, and therefore transistor
Q ₁ is turned OFF, V ₀ is lowered to 0, and power supply to the load is stopped.

Next, to explain the next call, when sending a call, the press talk button is pressed to send a call, and this button releases the R point of the press talk switch _S3 and grounds the T point. For this reason, _the volume R 11 is added to the resistor R ₈ , volume R ₉ , and volume R ₁₀ of the voltage comparison voltage divider, so the volume R ₉ is kept in the receiving state, and the volume R ₁₁ is adjusted so that V ₀ is lower than 9.5V. Adjust so that the voltage comparator _U1 turns OFF when the voltage drops slightly. The diode D ₁ is grounded by the grounding of the contact T, which lowers the base voltage of the transistor Q _4. Therefore, the transistor Q ₄ is turned on, the resistor R ₂ is shorted, and the transistor Q ₁ is in a high current operation state, and the voltage is changed from T ₀ . Power the load.
Next, if battery B over-discharges during transmission and V ₀ falls below the initially set voltage of 9.5V, comparator U ₁
is OFF as before, and transistor Q ₃ is OFF.
Therefore, the capacitor C ₁ is charged, turning off the transistor Q ₂ and therefore turning off the transistor Q ₁ to stop the power supply. In this state, even if the battery voltage V _B rises, the power supply remains OFF, and the operation of this circuit remains stopped.

Next, when press talk switch S ₃ is turned OFF and power switch S ₁ is turned OFF, switch S ₂ is turned ON, discharging the charging voltage of capacitor C ₁ via resistor R ₄ , and activating the transistors Q ₁ and Q ₂ system. give.
Now, when the power switch _S1 is turned on again, if the battery voltage _VB has recovered by the time the received voltage is supplied, _V0 will be supplied from the output terminal _T0 in the same manner as described above. However, this state does not last long, and as the comparator U ₁ OFF capacitor C ₁ is charged, the transistors Q ₁ and Q ₂ are turned OFF and the power supply is stopped.

In the above embodiment, the operating conditions at the time of transmission are described as using a transfer switch type press-to-talk switch, but this is similar to the conventional example by using a switch that is set at press time and a transistor circuit as shown in Fig. 3. Replacement is also possible.

In Figure 3, Vc is the power supply terminal, _S4 is the make switch for press talk, T is connected to the position corresponding to the T terminal and R is the R terminal in Figure 2, and in this case,
No need for _S3 . Q ₅ , Q ₆ are transistors, R ₁₄ ,
R ₁₅ is the collector resistance of Q ₅ and Q ₆ , R ₁₃ is the base resistance of Q ₅ , and Vc is applied when S ₄ is OFF. To explain this operation next, when switch S ₄ is OFF, Q ₅ is in the operating state, and point R is
Grounded via _D2 . Also, Q ₆ is OFF,
The T point rises to Tc, but backflow is prevented at _D1 .
Next, when you press the press talk button, S ₄ turns ON, grounding the base of transistor Q ₅ .
Therefore, _Q5 is OFF and the potential of the collector is Vc
However, diode D ₂ prevents reverse flow. At the same time, _Q6 is turned ON, and the T point is lowered to almost zero potential, and the operation is almost the same as that of the transfer switch _S3 in FIG. 2.

Further, unlike the above-mentioned embodiments, the same technique can be applied to a case where the transmitter is automatically activated, such as a public car telephone of the simultaneous transmitting/receiving type.

As explained above, according to the present invention, the power supply can be stopped at the battery discharge end voltage that is adapted to each usage condition during transmission, so in any case, the battery must be over-discharged before use. It has the advantage that it does not disable it or shorten its lifespan. In particular, according to the present invention, once the output voltage of the first transistor becomes lower than the discharge end voltage during transmission and reception, the third transistor is turned off, and the power supply through the first transistor is cut off. Then, unless the first switch is turned off and turned on again, the power supply through the first transistor continues to be cut off, and therefore,
Thereafter, even if the output voltage of the battery itself recovers, the power supply will not be restarted at all, and there is an advantage that over-discharge can be accurately prevented. According to the present invention, by turning off the first switch and then turning it on again, the first transistor can be turned on again, and if the output voltage of the battery has been recovered, the power continues to be supplied. It has the advantage that it can be supplied.

In addition, according to the present invention, the power supply is not only cut off at the end of discharge voltage when transmitting and receiving, but also when transmitting by using the activation switch and the fourth transistor to switch between transmitting and receiving. It is configured to automatically supply more load current than when receiving it, and can more faithfully relate the relationship between load current and battery end-of-discharge voltage, resulting in better overdischarge. It can be a prevention device. In other words, in general, in the case of press talk radio equipment, etc., the amount of current supplied to the load is different during transmission and reception, and the end voltage is increased during transmission, where a large amount of current is supplied, compared to when receiving, where a small amount of current is supplied. Otherwise, there is a problem of over-discharging, but according to the present invention, a larger load current can be automatically supplied during transmission than when receiving, and the end voltage can be made larger than when receiving. This has the advantage of effectively preventing over-discharge during both transmission and reception. Further, according to the present invention, the circuit structure as a whole is relatively simple and therefore inexpensive, and can be used in automobile radio telephones, small portable radio telephones, etc., and is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram of an overdischarge prevention device according to an embodiment of the present invention, FIG. 2 is a characteristic diagram of battery operating current and final voltage, and FIG. 3 is a wiring diagram of main parts of another embodiment. Q ₁ , Q ₂ , Q ₃ ... Transistor, U ₁ ... Voltage comparator, R ₁₁ ... Volume, C ₁ ... Capacitor, S ₁
……Power switch, S ₂ ……Switch, S ₃ ……Press talk switch.

Claims (1)

[Scope of utility model registration request] a first transistor connected in series to the power supply line to supply power to the load; a second transistor connected in series to the base of the first transistor to control the operating state of the first transistor; a voltage comparator that compares a value obtained by dividing the output voltage to the load by a voltage dividing circuit with a reference voltage;
a capacitor connected between the base of the second transistor and ground; a third transistor whose collector and emitter are connected to both ends of the capacitor; and whose base is coupled to the output terminal of the voltage comparator; a fourth transistor connected in series with the transistor and controlling the current flowing to the base of the first transistor through the second transistor; a first switch provided on the power supply side of the power supply line; a second switch that operates in conjunction with the first switch and forms a loop that discharges the charge in the capacitor when the first switch is off; and a ground side that forms the voltage divider circuit when turned on to the receiving side. A comparator is used to compare the terminals of a resistor installed at the terminal with the final voltage at the time of reception. 4. An overdischarge prevention device equipped with a start switch for transmission that turns on transistor No. 4, increases the current flowing to the base of the first transistor through the second transistor, and increases the amount of current supplied to the load.