JP3077209B2 - Voltage detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage detection circuit for detecting the state of an internal battery, and is used, for example, for detecting the voltage of an internal battery in a high-frequency therapeutic device.

[0002]

2. Description of the Related Art Hitherto, a high-frequency therapeutic device which promotes blood circulation and recovers from fatigue by irradiating a human body with a high-frequency magnetic field has been put to practical use. FIG. 3 shows a configuration of a conventional high-frequency treatment device. In the figure, 1 is a CR oscillation circuit, 2 is a timing control circuit, 3 is a charging circuit, 4 is an LED boost circuit, 5
Denotes a detection circuit, 6 denotes an internal battery, and 7 denotes an LED (light emitting diode). In this circuit, the timing control circuit 2 generates two timing signals A and B based on the oscillation output of the CR oscillation circuit 1. The timing signal A is supplied to the charging circuit 3, and the timing signal A
The charging circuit 3 charges the internal battery 6 when is at a high level, and does not charge when it is at a low level. The timing signal B is supplied to the LED boosting circuit 4. The LED boosting circuit 4 causes the LED 7 to emit light when the timing signal B is at a high level, and the LED 7 emits light when the timing signal B is at a low level.
ED7 does not emit light. The detection circuit 5 detects the voltage state of the internal battery 6 by a comparator, and sends a detection signal to the timing control circuit 2. The timing control circuit 2 controls the cycle and duty of the timing signals A and B according to the voltage state of the internal battery 6.

[0003]

In the prior art, the comparator of the detection circuit 5 detects a voltage fluctuation of the internal battery 6 which occurs when a large current is supplied such as when the internal battery 6 is charged or when the LED 7 emits light. This has the disadvantage of causing malfunctions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a voltage detection circuit for detecting the voltage of an internal battery which is affected by voltage fluctuations caused when a large current is supplied. It is to make it difficult.

[0005]

In order to solve the above-mentioned problems, a voltage detection circuit according to the present invention has a detection circuit 5 for detecting a state of an internal battery 6 and a control circuit for controlling timing for operating the internal circuit. timing signal a, an apparatus comprising a timing control circuit 2 for generating a B, and the detection circuit 5 timing signal C for controlling so during large current not operate the detection circuit 5 from the timing control circuit 2 Input voltage detection
In the circuit, the detection circuit 5 buffers and amplifies an input voltage.
And one end of the buffer 10 is connected to the output end of the buffer 10.
Analog switch 11 and analog switch 1
A resistor 12 whose one end is connected to the other end of the
A capacitor 13 connected between the terminal and the ground potential;
Always monitor the analog potential of the capacitor 13 (Comparator
Circuit means (e.g.,

[0006]

According to the present invention, timing signals A and B for controlling the timing for operating the internal circuit are generated by the timing control circuit 2, and the state of the internal battery 6 is detected from the same timing control circuit 2. Since the timing signal C for stopping the operation of the detection circuit 5 when a large current is supplied is generated, a malfunction due to the voltage fluctuation of the internal battery 6 that occurs when the large current is supplied can be eliminated. Also, the internal battery
The detection circuit 5 for detecting the state of 6 is a buffer amplifier for the input voltage.
And one end of the buffer 10 is connected to the output end of the buffer 10.
Analog switch 11 and analog switch 1
A resistor 12 whose one end is connected to the other end of the
A capacitor 13 connected between the terminal and the ground potential;
Always monitor the analog potential of the capacitor 13 (Comparator
And circuit means (e.g.,
So that high frequency noise can be removed and analog
This is effective when a logging value is required.

[0007]

FIG. 1 is a circuit diagram of an embodiment of the present invention. The input voltage Vin from the internal battery 6 is divided by resistors 8 and 9 for voltage division.
, And is input to the non-inverting input terminal of the buffer 10. The output terminal of the buffer 10 is connected to the inverting input terminal. This buffer 10 is composed of an operational amplifier (op-amp) and has a very high input impedance and a low output impedance. Further, since the amplification factor is very high, the input terminal is in an imaginary short state (virtual short circuit) and has the same potential. Therefore, the voltage applied to the non-inverting input terminal is directly output to the output terminal. The voltage of the output terminal of the buffer 10 is supplied to the capacitor 1 via the switch 11 and the resistor 12.
3 is applied. The voltage of the capacitor 13 is applied to the inverting input terminal of the comparator 14. A reference voltage Vref is applied to a non-inverting input terminal of the comparator 14. The output terminal of the comparator 14
An output signal Vout of the detection circuit is obtained.

Here, the switch 11 is an analog switch composed of a semiconductor element or the like, and is controlled by a timing signal C from the timing control circuit 2. When the timing signal C is at the high level, the switch 11 is turned on, the output voltage of the buffer 10 is applied to the capacitor 13 via the resistor 12, and the voltage of the capacitor 13 is compared with the reference voltage Vref by the comparator 14. When the timing signal C is at the low level, the switch 11 is turned off, and the output voltage of the buffer 10 is not transmitted to the comparator 14. At this time, the voltage held in the capacitor 13 is compared by the comparator 14 with the reference voltage Vref. That is, the comparator 1
Since the input impedance of the inverting input terminal 4 is very high, when the switch 11 is OFF, both ends of the resistor 12 are opened, and the capacitor 13 loses a discharge path. This holds the voltage state immediately before the start. The switch 11 is ON / OFF controlled by a timing signal C from the timing control circuit 2, so that the switch 11 is turned on during a period in which the high-frequency therapy device does not charge or emit LED light.

FIG. 2 is a waveform chart showing the operation of the present embodiment. In the figure, A is a charging timing signal output from the timing control circuit 2, and B is an LED light emission timing signal output from the circuit 2. As described with reference to the conventional example shown in FIG.
When the signal is at the high level, charging is performed, and when the signal is at the low level, charging is not performed. When the timing signal B is H
LED emission is performed at the high level, and LED emission is not performed at the low level. Therefore, a timing signal C which becomes High level only when both the timing signals A and B are Low level is generated, and the switch 11 shown in FIG. 1 is turned ON only when this timing signal C is High level. Note that the pulse width of the timing signal C is set slightly smaller than the range shown by the broken line, so that noise is not picked up when switching between the high level and the low level.

In the above embodiment, the case where the present invention is applied to a high-frequency therapeutic device has been described. However, in general, the present invention can be applied to any device that is intermittently supplied with power from an internal battery by a timing control circuit. it can.

[0011]

As described above, in the voltage detection circuit of the present invention, the operation of the detection circuit for detecting the state of the internal battery is controlled under the control of the timing control circuit for controlling the operation timing of the internal circuit. Since the operation is stopped when the power is supplied, there is an effect that a malfunction due to a voltage change of the internal battery which occurs when a large current is supplied can be avoided. In addition, a detection circuit that detects the state of the internal battery
A buffer that amplifies the voltage and a buffer
Analog switches with their ends connected and analog switches
A resistor whose one end is connected to the other end of the
Between the capacitor and the capacitor analog
Circuit means for constantly monitoring the switching potential.
It also has the effect of removing high-frequency noise.
This is effective when analog values are required.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of one embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 CR oscillation circuit 2 Timing control circuit 3 Charging circuit 4 LED booster circuit 5 Detector circuit 6 Internal battery 7 LED 8 Resistor for voltage division 9 Resistance for voltage division 10 Buffer 11 Switch 12 Resistance 13 Capacitor 14 Comparator A Charge timing signal B LED light emission Timing signal C Voltage detection timing signal

Continuation of the front page (56) References JP-A-53-143264 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/36

Claims (1)

(57) [Claims] A detection circuit as claimed in claim 1] for detecting a state of an internal battery, an apparatus comprising a timing control circuit for generating a timing signal for controlling the timing for operating the internal circuit, the operation of the sensing circuit at the time of large current In a voltage detection circuit in which a timing signal for controlling not to be input is input from the timing control circuit to the detection circuit, the detection circuit includes an input
A buffer that amplifies the voltage and a buffer
Analog switches with their ends connected and analog switches
A resistor whose one end is connected to the other end of the
Between the capacitor and the capacitor analog
Circuit means for constantly monitoring the voltage potential .