JPS6210058B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overdischarge prevention device for press talk type radio equipment, etc.

Conventionally, the operating current of press talk radios during standby is 0.1A or less, and in order to prevent over-discharging of the battery due to forgetting to turn off the switch, it is necessary to set the final voltage of the low current as the operating limit value. be. When transmitting using the press talk button, the operating current is several amperes, and the output voltage of the battery is
The output voltage decreases according to the output curve in the figure, and when the output voltage falls below the final voltage, the over-discharge prevention circuit operates and cuts off the power supply to the transmitter, but this voltage is still sufficient for use. Because of the current situation, there was a problem with the way it was used, and some kind of countermeasure was needed.

The present invention was made in view of these problems, and if you forget to turn off the switch during standby, it detects the final voltage and automatically turns off the power. Considering that it is rare to over-discharge the battery by continuously pressing the button unnecessarily, and focusing on the fact that continuing to transmit near the battery's final voltage is an emergency call, we consider that this may cause some overuse of the battery. This also attempts to protect emergency calls by not forcibly interrupting calls in progress.

Fig. 2 shows an overdischarge prevention device according to an embodiment of the present invention, where T _C is a charging terminal, B is a built-in battery of a wireless device, S ₁ is a power switch, S ₂ is an operation prohibition release switch, and Q ₁ is an operation prohibition release switch. Switch transistor for current control, Q ₂ is a transistor for controlling transistor Q ₁ , Q ₃ is a transistor for controlling transistor Q ₂ , Q ₄ is a transistor for controlling transistor Q ₁ during press talk, R ₁ is transistor Q for transmitting A resistor that controls the current of ₁ , R ₂
is a resistance that limits the current of transistor Q ₁ during reception together with transistor Q ₂ , R ₃ is a resistance that limits the operation of transistor Q ₂ , and R ₄ is the power switch OFF.
A series resistor, R ₅ , discharges the charge in capacitor C ₁ by grounding switch S ₂ when .
_R6 is a voltage dividing resistor of transistor _Q4 , and _R7 is a series resistor of Zener diode _Z2 , which supplies a comparison voltage to one terminal of voltage comparator _U1 . R ₈ , R ₉ , and R ₁₀ are resistors forming a voltage dividing circuit for the output voltage, and R ₉ is a variable resistor that supplies a voltage to the + terminal of the voltage comparator U ₁ . _R11
is the series resistance between the voltage comparator U ₁ and the Zener diode Z ₁ , C ₂ is the noise bypass capacitor, T _P is the relay terminal of the pre-talk switch S _P , and by closing the pre-talk switch _SP and grounding it, the resistor R ₆ to ground through diode _D1 . T _O
is an output terminal, and L is a radio device as a load of the battery.

Next, the operation to prevent forgetting to turn off the switch during reception will be explained. When power switch _S1 is turned on, _S1 is connected and voltage is applied to transistor _Q1 .
At the same time, capacitor C ₁ is unshot by switch S ₂ , but if its capacitance is chosen to be relatively large, its potential is initially close to zero, so that transistor Q ₂ is operated, and transistor Q ₁ provides an output to output terminal T _O. Next, _the voltage comparator _U1 compares the input voltage from the Zener diode _{Z2 and the} voltage from the resistor _R9 . Outputs a voltage, and when this is higher than the zener voltage of zener diode _Z1 , the transistor
Make Q ₃ conductive, shoot capacitor C ₁ , operate transistor Q ₂ , and turn on transistor Q _1.
continues to supply power to the load with the current in a conductive state. When the output voltage V _O decreases and the voltage from the resistor R ₉ becomes lower than the voltage from the Zener diode Z ₂ , the output of the voltage comparator U ₁ becomes almost OV, and the voltage from the transistor Q ₃
is non-conducting. Next, the base current of transistor Q ₂ charges the capacitor C ₁ and increases the base voltage of transistor Q ₂ , making transistor Q ₂ non-conductive, and the output of transistor Q ₁ becomes approximately OV.

Next, the state of the press talk call will be explained.

Press button, which is generally attached to the microphone, activates the press talk switch S.
_P is shorted and the resistor _R6 is grounded through the Zener diode _D1 , which activates the bypass transistor _Q4 and grounds the base of the transistor _Q1 through the resistor _R1 .

Therefore, the transistor Q ₁ outputs the current determined by the resistor R ₁ to the transmitter via the output terminal T _O.

Next, when you return the press button, the Zener diode
The terminal voltage of Z ₂ is set to the final voltage when the current is low, but if the battery is extremely depleted at this time, transistor D ₃ will become inactive and no power will be supplied to the receiver, which will alert you to a power failure. be able to.

Also, insert a voltmeter M and a Zener diode Z ₃ in series between the output terminal of the switch S ₁ and the contacts of the resistor R ₃ and capacitor C ₁ , or
Instead, it is also effective to monitor the charging voltage using an indicator replaced with a light emitting body such as a light emitting diode or a small lamp.

As explained above, in the present invention, when the over-discharge prevention circuit due to forgetting to turn off the switch is set to the battery final voltage at a low current such as during reception, this circuit cuts off the power supply during a press talk call and prevents transmission. However, during this time, the switch transistor is forcibly operated by a separate circuit, and when the press button is released, the over-discharge prevention circuit is immediately set to the reception condition, which prevents over-discharge during communication. It is effective when used as a circuit. In addition, over-discharge caused by forgetting to turn off the switch can be prevented by cutting off the power supply path when the battery's output voltage drops below a certain value, and it is possible to operate even when the battery's output voltage is low during transmission, which prevents over-discharge. This can prevent the functionality of the radio from deteriorating.

[Brief explanation of the drawing]

FIG. 1 is a final voltage characteristic diagram of a battery, and FIG. 2 is a wiring diagram of an overdischarge prevention device in an embodiment of the present invention. B... Built-in storage battery, L... Radio, Q ₁ ...
Transistor for current control, S _P ... Press talk switch, Q ₄ ... Transistor for bypass.

Claims (1)

[Claims] 1 Equipped with a power supply control means inserted between a built-in storage battery and a radio device serving as its load, which detects when the output voltage of the storage battery becomes equal to or lower than the battery's own termination voltage and shuts off the power supply control means. In the over-discharge prevention device, the over-discharge prevention device prevents over-discharge of the storage battery by setting the above-mentioned over-discharge prevention device to the above-mentioned state. Features an overdischarge prevention device.