JPS5917892B2 - multi vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement for reducing power consumption of a multivibrator using a C-MOS IC inverter circuit.

C-MOSIC originally has low power consumption and operates completely on batteries.
Because it has characteristics such as being resistant to external noise, it is often used in so-called single-station fire alarms that use primary batteries as a power source.

For example, a single-station fire alarm with a built-in ionization smoke detector uses a DC-DC converter that includes a multivibrator using a C-MOS inverter to obtain a high voltage to be applied to the ion chamber of the detector. It is desirable to reduce the power consumption of this multivibrator itself as much as possible as a load on the battery.

By the way, most of the conventionally used multivibrators have the configuration shown in Figure 1, in which two C-MOS inverters 1 and 2 are used to convert the differential voltage flowing through a resistor 3 and a capacitor 4. Periodic changes in the potential Va at point a caused by current are taken out as pulses from point b or d.

To explain the operation of the conventional multivibrator shown in FIG. 1, in the waveform shown in FIG. 2, the potential Va at point a becomes t due to the time constant determined by the resistor 3 and capacitor 4.

, U1tj2, etc., each changes periodically.

At time to, the output of inverter 1 is at a high potential level r
The potential level is inverted from HJ to the low potential level rLJ, and the output of the inverter 2 is instantaneously inverted from "L" to "H".

Therefore, until now, the bias across the capacitor 40 was negative on the side of point d and positive on the side of point a, but now it is t.

At this point, Va is biased to the opposite potential, and Va momentarily becomes VDD+
It rises to about the same level as a VTR.

At the time from 1o to t1, the P channel M of inverter 2
Inverter 1O from O8 via capacitor 4 and resistor 3
A differential current flows through the N channel MO8, and Va gradually decreases from the "H" level.

At the time tl, the gradually decreasing Va reaches the inverter 10 circuit threshold voltage vT, and as a result, both inverters 1 and 2 are inverted, and the potential at point b changes from rLJ to rH.
At J, the potential Vd at point d changes from rHJ to rLJ.

As a result, the capacitor 4 is reverse biased again, and Va momentarily drops to around -VTH.

At the time from Ll to t2, a differential current flows from the P channel O8 of the inverter 1 to the inverter 2ON channel MO8 via the resistor 3 and capacitor 4 in order, and Va gradually increases until it reaches the inverter 10 circuit threshold voltage at the time t2. V
T is reached, and the state is the same as at the 18th point.

In a diagram of such an operation, the output taken from point d, for example, becomes a constant-period oscillation output.

In FIG. 2, ■ indicates a temporal change in the current consumption of this circuit, which indicates that Va tends to increase near the inverter 10 circuit threshold voltage.

Therefore, when the oscillation period of the multivibrator is set short, the current consumption becomes so large that it cannot be ignored, especially if the change when Va passes through the threshold voltage is slow.

This invention was made in view of the above-mentioned problems, and it makes the change when the above-mentioned Va exceeds the threshold potential of the circuit steeper,
Therefore, it is an object of the present invention to provide a multivibrator that consumes less current even with a short oscillation cycle.

That is, in the multivibrator of the present invention, in a multivibrator using two C-MOS inverters, the change in the differential current applied to the input terminal of one C-MOS inverter is made steep through the transistor, and thereby the inverter This shortens the time interval during which current consumption flows near the threshold, thus greatly contributing to reducing power consumption of the power supply, and also allows controlling the bias of the transistors from the outside to control the start and stop of oscillation of the multivibrator. It is possible to increase the additional value of use, such as by making it more useful.

The multivibrator of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a basic circuit diagram of the multivibrator of the present invention, in which 10 is a 10th C-10C-inverter, 11 is a second C-MOS inverter, and the output end of the inverter 10 is connected to the input end of the inverter 110. Both inverters are connected in series.

12 is a positive power supply terminal to which a voltage of +VDD is applied, and 13 is a negative current terminal to which -VSS is applied; in reality, the terminals 12.
A battery is connected between the terminals 13 and 13, and the above VDD+VSS corresponds to the electromotive voltage of this battery.

Inverters 10 and 11 are connected to power terminals 12.1 and 12.1 as shown in the figure.
3 are connected in parallel, and a transistor 1 is connected between the power supply terminals.
4 and a second resistor 15 are connected in series.

That is, the transistor 14 is of a PNP type, and its emitter electrode is connected to the positive power supply terminal 12, and its collector terminal is connected to the negative power supply terminal 13 via the second resistor 15.

The second resistor 15 has a sufficiently large value so that the current when the transistor 14 is conductive is extremely small.

The connection point between the collector terminal and the second resistor 15 is connected to the input terminal of the first inverter 100, while the output terminal of the second inverter 11 is connected to the first resistor 16 and the capacitor 1γ in series. The connection point between the first resistor 16 and the capacitor 11 is connected to the base electrode of the transistor 140.

Although the output terminal 18 of the multivibrator is taken out from the output end of the second inverter 11 in the illustrated example, it may be taken out from the output end of the first inverter 10 when an inverted output is desired.

The operation of the circuit shown in FIG. 3 is such that if the values of the circuit elements are selected so that the transistor 14 is turned on at the same time as the power supply voltage is applied, the potential Va at point a is at a high potential level at the same time as the transistor 14 is turned on. At rHJ, the potential at point b, vb, is at the low potential level "L", and the potential at point d, Vd, is at the high potential level, r.
Becomes HJ.

Therefore, a current flows from the terminal 12 to the capacitor 11 via the path between the P channel O8 of the inverter 11 and the resistor 16, and the emitter base path of the transistor 14, and further from the capacitor 11 to the inverter 100 via the N channel MO8 to the negative power supply terminal 13. Let the current flow to.

As a result, the base potential of the transistor 14 gradually increases due to the charge in the capacitor 11, and eventually the transistor 14 switches to OF''F.

When the transistor 14 is turned off, Va becomes rLJ, v
b becomes rHJ and Vd becomes "L", and current flows from the terminal 12 to the terminal 13 through the P-channel O8 of the inverter 10, the capacitor 11, the resistor 16, and the N-channel MO8 of the inverter 11 in this order, and the The potential is gradually lowered, and eventually the transistor 14 becomes O again.
Switch to N.

This operation is diagrammed to show that the circuit oscillates at a fixed period, and the output terminal 1
The oscillation output is taken out from 8 to the outside.

The base potential of the transistor 140 in the above operation, a
FIG. 4 shows changes in the potential Va at a point and the potential Vd at a point d, with the time axis as the horizontal axis.

In addition, in the example of FIG. 3 above, the transistor 14 is a PNP.
Although the case where a transistor 14' of NPN type is used is shown, this may be constructed using an NPN type transistor 14' as shown in FIG.
, are almost the same except that the OFF state is reversed from that of the transistor 14.

In any case, a relatively slow change in the base potential of the transistor 14 or 14' becomes a steep change on the collector side due to the switching operation, and therefore the change in the point a potential Va becomes steep, causing the threshold potential of the inverter 10 to change instantaneously. As a result, the time-integrated value of the current consumption in the inverters 10 and 11 becomes extremely small, and the power consumption of the power source is reduced.

FIG. 6 is a circuit diagram of an embodiment in which the multivibrator of the present invention is used in a single station fire alarm.

In FIG. 6, 100 is a smoke detection circuit, and internal ionization chambers 102 are ionized together by one radiation source 101.
The ionization type smoke detector 10γ includes an internal electrode 104, an intermediate electrode 105, and an external electrode 106, which constitute an external ionization chamber 103.

The external ionization chamber 103 is configured to allow smoke to easily enter from the outside, while the internal ionization chamber 102 is configured to prevent smoke from easily entering.

The field effect transistor 108 whose gate electrode is connected to the intermediate electrode 105 has a voltage that normally appears at the intermediate electrode as a predetermined divided potential due to an ionization current flowing in accordance with the voltage applied to the external electrode 106 and the internal electrode 104. The radiation intensity of the radiation source 1o1, the distance between each electrode, etc. are set so that this @off state can be obtained.

When smoke from a fire enters the external ionization chamber 103, the above ionization current changes, the partial pressure state changes, and the intermediate electrode 105
When the potential of the transistor 108 decreases to a predetermined value, the transistor 108
conducts.

An alarm buzzer is activated by the conduction output of this transistor 108.
Two inverters 110,1 are used to operate 109.
11 and a transistor 112.

In this fire alarm, the power source is comprised of a normal dry cell battery 113, and therefore the size can be reduced without using any special batteries.

Therefore, the power source is a low voltage, and only the ionization voltage applied between the external electrode and the internal electrode is high voltage.

That is, this high voltage is applied to the booster circuit 1 forming a triple voltage rectifier circuit with the first multivibrator 114 according to the present invention.
15 from the dry cell battery 113, and by applying such a high voltage to the ionization chambers 102 and 103, the potential change due to smoke in the smoke detection section is increased, thereby ensuring reliable operation.

The power supply voltage to the circuit elements other than the above ionization chamber is the above dry battery 1.
A voltage detection circuit 11γ directly uses the electromotive voltage of 13 and causes the multivibrator 114 to oscillate only when the output voltage value of the booster circuit 115 falls below a predetermined value.
It is equipped with

In FIG. 6, the boosted voltage is a negative voltage such as -10V, and this and the positive electrode potential of the dry battery 113 are, for example, 4°5V.
The difference of 14°5V between the inner and outer electrodes 104106 is the voltage applied between the inner and outer electrodes 104106.

The output voltage of the booster circuit 115 is supplied to the internal electrode 104 and is also supplied to the resistors 118, 119, 1 of the voltage detection circuit 111.
20 and Zener diode 121 in series circuit load.

The decrease in the output of the booster circuit 115 causes an increase in the potential at the connection point X between the resistors 118 and 119, thereby biasing the transistor 122 in the multivibrator 114 to the OFF state.

As a result, the input terminal of one C-MOS inverter 1230 becomes a low potential level "L", and the output terminal becomes a high potential level rHJ, so that the other C-MOS inverter 1230
The input end of 4 is rHJ, and the output end is rLJ.

As a result, the positive electrode of the dry battery 113 → P of the inverter 123
Channel MO8 → Capacitor 125 → Resistor 126 → Inverter 124 ON Channel MO8 → Current flows in the negative electrode loop of dry battery 113, and the base potential of transistor 1220 decreases from the "H" level with a predetermined time constant, and the transistor 122 reaches a predetermined value. Switch to ON.

As a result, the input terminal of the inverter 1230 becomes rHJ, the output terminal becomes rLJ, the input terminal of the inverter 124 becomes rLJ, and the output terminal becomes rHJ.

As a result, the positive electrode of the dry battery 113, 47/Z −
32 P-channel Mos of transistor 124 → resistor 126 → emitter of transistor 122 → base capacitor 125 → inverter 123 ON channel M
A current flows in the loop from O3 to the negative electrode of the dry battery 113, and the base potential of the transistor 1220 gradually rises, and when it reaches a voltage approximately 0.6 V lower than the positive electrode voltage VDD of the dry battery 113, the transistor 122 is switched OFF. .

By turning off this transistor 122, the inverter 1
230 input terminal becomes rLJ, and oscillation is performed by following similar operations.

Due to the above oscillation operation, in the booster circuit 115, when the output terminal of the inverter 124 reaches rHJ, it is dry! ? 113
Positive pole → P channel MO8 of inverter 124 → Capacitor 121 → Diode 128 → Capacitor 129 →
N-channel MO3 of inverter 123 → dry battery 113
VDD to capacitors 127 and 129 in the negative loop of
-Vf/2 voltage is charged.

Note that the above Vf is a forward voltage drop of the diodes 128, 130, and 132, and is usually about 0.5 V.

Next, when the output terminal of the inverter 124 becomes rLJ, the positive electrode of the dry battery 113 → the inverter 1230P, the capacitor 129 → the diode, f'''MOS<,,, de, 31~2. Iode 130 'f7/'-112
The capacitor 129 is charged with a voltage of VDD-Vf in the N-channel MO3 of No. 4→the negative electrode of the dry battery 113, and the capacitors 131 and 121 are each charged with a voltage of VDD-Vf/2.

Therefore, the capacitor 133 has (VDD Vf)/2+((VDD-Vf)/2+(
VDo -Vf)/2. l+((VDD-Vf)+(V
A voltage of DD-Vf)/2)=3(VDD-Vf) is negatively charged to the negative electrode of the dry battery 113.

Boosting progresses in this way, and when the boosted voltage reaches a predetermined value, the potential at the connection point ON
bias towards.

By turning on this transistor 122, the multivibrator 114 stops oscillating, and thereby the booster circuit 11
The boosting operation of No. 5 is also stopped.

When the boosted voltage stored in the capacitor 133 is consumed by the ionization chamber and the resistance of the voltage detection circuit 117, and its potential decreases (approaches a positive potential), the potential at the connection point X increases and turns off the transistor 122. When the transistor 122 is switched off, the multivibrator 114 resumes oscillation and the capacitor 133 of the booster circuit 115 is charged again in the same manner as described above.

The diagram of the above operation shows that the charging potential of the capacitor 133 is maintained at a predetermined level.

Another multi-vibrator 116 is used to intermittently sound an alarm buzzer 109 when the electromotive voltage of the dry battery 113 has decreased to a certain value, thereby prompting battery replacement with an alarm other than a fire alarm. .

That is, in FIG. 6, the resistance 1 of the voltage detection circuit 111
Reference numeral 19 denotes a variable resistor from which an arbitrary potential more negative than the potential at the connection point X is taken out from the movable contact terminal Y.

When the electromotive voltage of the dry battery 113 is sufficiently high and the above-mentioned voltage increase is sufficient, the variable resistor is set in advance so that the potential of the movable contact end Y is lower than the VBE of the transistor 134. has been done.

Therefore, in this state, the transistor 134 is conductive, the input terminal of the inverter 1350 is "H", the output terminal is "L", the input terminal of the inverter 136 is "L", and the output terminal is "H".

Even in this state, the base potential of the transistor 1340 maintains the ON bias balance.

The battery voltage decreases and the potential of the movable contact end Y reaches a predetermined value V
When rising to the DD side, the base of transistor 1340 becomes O.
It becomes F'F' bias and turns off the transistor 134.
As a result, the multivibrator 116 starts oscillating.

In this case, a resistor 131 is inserted into the base of the transistor 1340 to suppress the flow of base current, and the duty ratio of oscillation is brought close to 50%.

The output of this multivibrator 116 is the capacitor 13
8 and a resistor 139
11 and is input to buzzer 1 via transistor 112.
Connect 09 to the power supply in a pulsed manner to make the buzzer sound intermittently.

The values of the circuit elements are selected so that this ringing occurs intermittently for a short period of time, for example, once every 30 seconds.

It goes without saying that the operation starting point of the multivibrator 116 can be arbitrarily selected by adjusting the movable contact end Y of the variable resistor 119.

As described above, in the multivibrator of the present invention, the connection point between the resistor and the capacitor where charging and discharging is performed is inputted to the C-MOS inverter via the switching transistor connected between the power supplies. , it is possible to speed up the passage of the input voltage change to the threshold value of the inverter, and it is possible to reduce the power consumption during switching of the inverter.

In addition, by controlling the bias of the switching transistor and controlling conduction 1 from the outside, it is possible to easily control the start and stop of oscillation of the multivibrator. for(
If so, various effects can be achieved, such as reducing current consumption, warning of low battery voltage, and boosting voltage with low power consumption.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the basic configuration of a conventional multivibrator, Fig. 2 is a time chart diagram showing operating waveforms of the one in Fig. 1, and Fig. 3 is a circuit diagram showing the basic configuration of the multivibrator of the present invention. , FIG. 4 is a time chart diagram showing operating waveforms of the one in FIG. 3, FIG. 5 is a circuit diagram showing a multivibrator according to another embodiment of the present invention, and FIG. 6 is a diagram showing a multivibrator using the multivibrator of the present invention. This is a circuit diagram of a fire alarm. 10... First C-MOS inverter, 11... 20th C-MOS inverter, 14... Transistor,
15...Second resistance, 18...First resistance, 11.
...Capacitor.

Claims (1)

[Claims] 1 Connected in parallel to the DC power supply 1st and 20th C-M
It comprises an OS inverter, a capacitor, a first resistor, and a series circuit of a transistor and a second resistor connected in parallel between the power supplies, and the input terminal of the first C-MOS inverter is connected to the transistor of the series circuit. and the second resistor, and the output terminal of the 10th C-MOS inverter is connected to the input terminal of the 20th C-MOS inverter,
The output end of the 20th C-MOS inverter is connected to the second C-MOS inverter through the first resistor and the capacitor in series.
A multivibrator, characterized in that it is connected to an input end of a MOS inverter, and a connection point between the capacitor and the first resistor is connected to a base electrode of the transistor.