JPS6057252B2 - Battery voltage drop detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery voltage drop detection circuit that detects a battery voltage drop using the reception characteristics of a super regenerative radio receiver, and its purpose is to The purpose is to reduce fluctuations in the detected value of battery voltage due to variations, temperature changes, etc. Another purpose is to simplify the circuit configuration; The purpose is to detect the drop at an early point in time to prevent it from interfering with circuit operation.

As shown in Fig. 1, the conventional battery voltage drop detection circuit connects a resistor RB to a Zener diode ZD in series, connects it to the base of a transistor T, and connects it to a battery B, and connects the collector of the transistor T through a resistor Rc. was connected to battery B to detect a voltage drop in battery B. That is, the Zener voltage of the Zener diode m is used as the reference voltage, and when the voltage of the battery B is higher than the Zener voltage, the Zener diode ZD
and transistor T are both turned on, and the output voltage from the collector becomes L level. When the voltage of battery B becomes lower than the Zener voltage, transistor T is turned off, and the output from the collector becomes H level, and the battery voltage decreases. can be detected. However, this device has the disadvantage that the detected value of the battery voltage decreases due to variations in the Zener diode or changes in the temperature of the circuit, resulting in very large fluctuations. The present invention has been made in view of this point, and will be explained in detail below with reference to Examples.

The basic element of the present invention is a super regenerative radio receiver, and first, the super regenerative radio receiver will be explained.

As shown in FIG. 2, the super regenerative radio receiver is comprised of an antenna 1, a super regenerative front end 2, a low frequency amplifier 3, a bandpass filter 4, a signal level discrimination circuit 5, and a display 6 such as a buzzer. ing.

As shown in FIG. 3, the super-regeneration front end 2 is comprised of a buffer amplifier 7, a quenching oscillation circuit 8, and a low-pass filter 9, and this specific circuit is constructed as shown in FIG. Figures 5 a-c are voltage waveform diagrams at points A-C in Figure 4 when no signal input is present, and Figures 6 a-C are voltage waveform diagrams at points A-C in Figure 4 when signal input is present. It is a voltage waveform diagram. Now, the receiving power received by the antenna 1 is as shown in Figure 6a, and this signal voltage is amplified by the buffer amplifier 7 in Figure 3, resulting in an output as shown in Figure 6b. The output voltage is mixed with the quenching output voltage in the quenching oscillation circuit 8 which generates the output voltage, and is converted into a low frequency output as shown in FIG. 6c by the low pass filter 9.

This low frequency signal is amplified by the low frequency amplifier 3, but since this output actually includes noise, the band pass filter 4 distinguishes the signal from the noise. The signal component selected by the bandpass filter 4 is converted into a DC voltage corresponding to its amplitude by the signal level discrimination circuit 5, and if the DC voltage level is larger than the specified value, it is considered to be a regular signal. If it is a signal, it is displayed on the display 6. Next, in FIG. 4, the buffer amplifier 7 is a grounded base type tuned amplifier, with a coil L1 and a capacitor C.
, and form a tuned circuit, which resonates with the carrier frequency of the input radio wave.

Resonant output is coupled capacitor. The resistor R5 and the capacitor C6 form an integrating circuit, and the transistor T2 is connected to the collector of the transistor T2 in the requenching oscillation circuit "8" by the capacitor C7. Connect to the collector of 3
Ku. A capacitor Cl is connected between the collector and emitter of the transistor T2. are connected to form the oscillation loop of the positive feedback oscillation circuit. Resistor t/LR8 and capacitor Cl2 are a CR parallel circuit, and are connected to transistor T2 via oscillation coil L3.
Connect it to the emitter of The oscillation principle of this four-quenching oscillation circuit 8 is as follows. Assume that the transistor T2 is now in a transition state from an on state to an off state.

At this time, the collector potential of the transistor T2 increases at a constant time constant by an integrating circuit formed by a capacitor C6 and a resistor R5. This change in collector potential is transmitted to the emitter of transistor T2 by capacitor ClO. Then, when the collector potential reaches its peak, in other words, when the current flowing through the oscillation coil L3 becomes minimum,
The transistor T2 is activated by the back electromotive force of the oscillation coil L3.
A bias voltage is generated at the base of l in the direction of turning on the transistor T2, so that the transistor T2 turns on quickly. When turned on, the oscillation coil L3 generates a back electromotive force in the direction of turning off the transistor T2, turning off the transistor T2, and the collector potential gradually rises by an integrating circuit including a capacitor C6 and a resistor R5. In this way, the transistor T2 repeats an on-off oscillation state. Capacitors C8 and C9 and a coil correspond to the on/off operation of this transistor T2! A transient voltage and current are generated in the parallel oscillator circuit composed of. In this state, the resonant output of the buffer amplifier 7 at the previous stage is input to this tuning circuit, and a kind of mixing is performed. As a result, the resulting modulated signal is detected by the low-pass filter 9. The subsequent operations are as described above. The above operation is performed when the voltage of battery B is appropriate and the quenching oscillation circuit 8 is operating normally, that is, maintaining quenching oscillation.

If the voltage of battery B is gradually lowered, the level of the quenching output will gradually and uniformly decrease as shown by curve a in Figure 7, but when a certain voltage is reached, the quenching output will become continuous oscillation. When the state changes from the state to the discontinuous oscillation state and the voltage of battery B is further lowered, the quenching output becomes completely zero. Next, the quenching oscillation period initially becomes longer due to the voltage drop of battery B, as shown by curve b in FIG.
As the voltage decreases further and approaches the quenching oscillation stop point, the period rapidly increases. Therefore, the voltage drop of battery B can be detected by the following detection method. A: Detects the transition point of quenching oscillation from continuous oscillation to discontinuous oscillation, and detects that the battery voltage is interfering with circuit operation at this point.

B: Detects when quenching oscillation has completely stopped.

C: When the cycle (or frequency) of quenching oscillation is detected and exceeds a certain value, it is detected that the battery voltage has dropped to a level that will cause problems in circuit operation.

There are three points above, and the order of detection time is C, A, and B.
becomes.

Next, a method for detecting a transition point to discontinuous oscillation will be explained.

FIG. 8 is a circuit diagram in this case, in which a parallel circuit of a diode D1 and a resistor Rl3 is connected to the collector of the transistor T3, and inverters INVl and INV2 are connected to its output side. 9a to 9c are waveforms at points P, Q, and R in FIG. 8, respectively. When the voltage of battery B is high, quenching oscillation exists, but when the voltage becomes low, discontinuous oscillation occurs. Therefore, when the voltage of battery B is high, transistor T3 is in an on state, but at the moment when the voltage becomes low and non-oscillation occurs, transistor T3 is turned off, and capacitor C
The potential of l7 rises with time constants Rl2 and Cl7, and when it reaches the threshold level of inverter INVl, it reaches point R.
It outputs a level output to detect a voltage drop in battery B.
Next, to detect the state in which the quenching oscillation has stopped, inverters INVl and INV2 are connected directly to the collector of the transistor T3 as shown in FIG. 10, and FIGS. These are the waveforms at each point of P, Q, and R.

When the voltage of battery B is high, quenching oscillation is present and transistor T3 is turned on, but when the voltage is low, quenching oscillation is no longer present and transistor T3 is turned off. When transistor T3 turns off,
The potential of the capacitor Cl7 increases with time constants R16 and Cl7, and when it reaches the threshold level of the inverter INV1, the R point becomes H level and a voltage drop is detected. Furthermore, as shown in FIG. 12, the device that detects the voltage drop based on the period of quenching oscillation is connected to the flip-flop F. F. and monostable multivibrator T.

, input these outputs to an AND gate, and AN
A is designed to obtain the detection output from the output of the D gate.
Ru. Figures 13 a to e are P, P'', Q, Q'' of Figure 12,
It is a waveform of each point of R. When the voltage of battery B is high, the period of quenching oscillation is short as shown by t1, and when the voltage is low, the period becomes long as shown by T2. Monostable multivibrator T. generates a pulse with pulse width T3 by the trigger of quenching oscillation, and when the voltage of battery B is high, it is t1, so there is no output from the AND gate, but when the voltage becomes low! >T3, and output is output from the AND gate to detect a voltage drop in battery B. As described above, the present invention detects a voltage drop in battery B when the quenching oscillation of the quenching circuit provided in the front end of the super regeneration system changes from continuous oscillation to discontinuous oscillation. Fluctuations in the detected battery voltage value due to variations, temperature changes, etc. can be reduced, improving detection accuracy.
In addition, since the battery voltage drop is detected when the quenching oscillation changes from continuous oscillation to oscillation stop, the circuit configuration can be simplified, and the quenching oscillation period can be longer than the preset period. Since the battery voltage drop is detected at the instant when the battery voltage drops, it is possible to detect the battery voltage drop at an early stage without causing any trouble to the circuit operation.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional battery voltage drop detection circuit, FIG. 2 is a block circuit diagram of a super-regenerative wireless receiver used in the present invention, and FIG. 3 is a block circuit diagram of the same super-regenerative front end. Figure 4 is a specific circuit diagram of the same as above, Figures 5 a to c are operation time charts when there is no receiver power as above,
6a to 6c are operation time charts when the receiver's power is present, FIG. 7 is a characteristic diagram of the quenching oscillation circuit, and FIG. 8 is a circuit diagram of an embodiment of the present invention. 9a-c are operation time charts of the same as above, FIG. 10 is a circuit diagram of another embodiment of the present invention, FIGS. 11a-c are operation time charts of the same as above, and FIG. The circuit diagram of the embodiment and FIGS. 13a to 13e are the same operation time charts as above.

Claims (1)

[Claims] 1. A quenching circuit provided at the front end of a super-regenerative system that converts received input into a low-frequency signal, and an integrating circuit connected to the collector of a transistor via a parallel resonant circuit consisting of a coil and a capacitor. A parallel circuit of a capacitor and a resistor is connected to the emitter of the transistor via an oscillation coil, and a capacitor is connected between the collector and emitter of the transistor to form a parallel circuit, so that the quenching oscillation of the quenching circuit is changed from continuous oscillation. A battery voltage drop detection circuit is configured to detect a battery voltage drop when continuous oscillation occurs. 2. The battery voltage drop detection circuit according to claim 1, wherein the battery voltage drop detection circuit is configured to detect a battery voltage drop when the quenching oscillation of the quenching circuit changes from continuous oscillation to oscillation stop. 3. The battery voltage according to claim 1, wherein the battery voltage drop is detected when the quenching oscillation cycle of the quenching oscillation circuit becomes longer than a preset cycle. Drop detection circuit.