JPS6412056B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a relay drive circuit that consumes less power. In particular, the present invention relates to improvements in drive circuits for output relays in burglar alarms. 2. Description of the Related Art Conventionally, a relay drive circuit as shown in FIG. 1 has been known as a low power consumption relay drive circuit. That is, when the switch _S1 is closed and the voltage E is applied to the series circuit of the coil of the magnetically holding type relay Ry and the capacitor C, the charging current _i1 of the capacitor C flows, and the magnetically holding type relay Ry is reversely operated. , when the switch S ₂ is closed, the discharge current of the electric charge stored in the capacitor C flows i ₂
This is a circuit for inverting and restoring the magnetic holding type relay Ry. The charging current i ₁ of this capacitor C,
As shown in Fig. 2, the discharge current _i2 initially flows as a large current and decreases as time passes, but if it is set so that the current is greater than the magnetic current _i0 of the magnetic retention type relay Ry, the magnetic Since it is a holding type relay, once it is reversed, it continues to be held even if the current becomes zero, so the power consumption required to reverse the relay is sufficient, making it an extremely low power consumption circuit.

However, security alarms and the like use extremely low voltages such as 5V or 3V DC to drive their circuits, and there are many complex circuits, so when connecting the power supply, the circuit is driven by a third voltage.
The power supply voltage will be applied to the circuit according to the curve shown in the figure, and when the power supply voltage is applied gradually in this way, the charging current of the capacitor C will be the third
The curve as shown in Figure i ₁ ′ is obtained, and the above-mentioned magnetic retention type relay
Ry's emotional current i may not exceed ₀ , and if the magnetic retention type relay Ry is not activated, the output relay of the burglar alarm will be in an alarm state, and when the burglar alarm is set to be installed, the state of the output relay will be reversed, causing a false alarm. state. In addition, in the case of a battery power supply, if the battery is used for a long period of time, the battery gradually discharges, the power supply voltage E decreases, and the charge accumulated in the capacitor C decreases, and even if switch S ₂ is turned on by an alarm input, the battery will gradually discharge. There was a problem that there was a risk that the current _i2 would not reach a value sufficient to reverse the magnetic retention type relay Ry, and that the normal alarm state would continue to be maintained despite the alarm state. In addition, the control input may also change gradually, and if _S1 in Figure 1 is a transistor and the control input is connected to the base of this transistor, the charging current of the capacitor C will change as in the previous case. may form a curve as shown in FIG. 8 i ₁ '.

This invention has been made to improve the above-mentioned drawbacks, and the specific invention is based on a capacitor that is connected in series to the coil of a magnetically held relay, and a charging current of the capacitor that flows when a voltage is applied to this series circuit. In the relay drive circuit, the magnetic retention type relay is operated in a reverse operation, and the magnetic retention type relay is reversed and restored by a discharge current that flows when the charged charge of the capacitor is discharged. a voltage detection means, and a switching element for driving the relay is brought into a non-conducting state if the power supply voltage is below a predetermined value;
When the power supply voltage becomes a predetermined value or more, the relay driving switching element is brought into a conductive state, and when the power supply voltage changes from a predetermined value or more to a predetermined value or less, the relay driving switching element is reversed to a non-conductive state. A quick-on, quick-break circuit such as a Schmidt circuit connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetically held relay, and a fast-on fast-break circuit such as a Schmidt circuit that connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetically held relay, and a fast-on fast-break circuit such as a Schmidt circuit that connects the power supply voltage to the series circuit of the coil and capacitor of the magnetically held relay, and a A relay driving circuit is characterized in that it includes a switching element that discharges a charged electric charge, and the combined invention is a relay driving circuit characterized in that a capacitor is connected in series to the coil of a magnetic holding type relay, and a voltage flows when a voltage is applied to this series circuit. In the relay drive circuit, the magnetic retention type relay is reversed by a charging current of a capacitor, and the magnetic retention type relay is reversed and restored by a discharge current flowing when the charge charged in the capacitor is discharged, and the power supply voltage is equal to or higher than a predetermined value. a switching element that connects the voltage detecting means to a power source according to another control input; and a switching element for driving the relay that is rendered non-conductive if the power source voltage is below a predetermined value;
When the power supply voltage becomes a predetermined value or more, the relay driving switching element is brought into a conductive state, and when the power supply voltage changes from a predetermined value or more to a predetermined value or less, the relay driving switching element is reversed to a non-conductive state. A quick-on, quick-break circuit such as a Schmidt circuit connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetically held relay, and a fast-on fast-break circuit such as a Schmidt circuit that connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetically held relay, and a fast-on fast-break circuit such as a Schmidt circuit that connects the power supply voltage to the series circuit of the coil and capacitor of the magnetically held relay, and a A relay drive circuit is characterized in that it includes a switching element that discharges a charged electric charge, and the specific invention provides a circuit that improves the drawbacks when the power supply voltage changes slowly,
The combined invention provides a circuit that ameliorates the disadvantages of slow changes in control inputs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below according to embodiments of a relay drive circuit.

In FIG. 4, reference numeral 1 denotes a voltage detection means constituted by a series circuit of a resistor _R1 and a Zener diode 2. Zener voltage of this Zener diode 2
V _Z is set to a value sufficient to make the value of the power supply voltage E ₁ a predetermined voltage, in other words, to give the impressed current i ₀ of the magnetically held relay 3 . The transistor Tr ₁ is connected in series with the series circuit of the resistor R ₁ and the Zener diode 2 constituting the voltage detection means 1, and the series circuit of the resistor R ₁ and the Zener diode 2 is connected by the control input Si input to the base. This is a switching element connected to a power source. Reference numeral 4 denotes a Schmitt circuit consisting of transistors Tr ₂ and Tr ₃ and resistors R ₂ , R ₃ and R ₅ . The input of this Schmitt circuit 4 is obtained by connecting the base of the transistor Tr ₂ to the connection point a between the resistor R ₁ and the Zener diode 2, and the output is obtained from the collector of the transistor Tr ₃ to the transistor Tr, which is a switching element for driving a relay. It is issued by connecting to the base of ₄ . The emitter of the transistor Tr ₄ , which is a switching element for driving the relay, is connected to the (positive) side of the power supply voltage, and the collector is connected to the series circuit 6 of the capacitor C ₂ and the coil 5 of the magnetic retention type relay 3, and the other end of this series circuit 6 Connect to the (negative) side of the power supply voltage. Tr ₅ connects the series circuit 6 to discharge the charge accumulated in the capacitor C ₂ of the series circuit 6.
A switching element connected in parallel with the relay driving switching element _Tr4 becomes conductive when the relay driving switching element Tr4 is in a non-conductive state. The resistor R ₆ forms a circuit for the base current of the transistor Tr ₅ , and the diode D makes the transistor Tr ₄ conductive by lowering the emitter potential of the transistor Tr ₅ below the base potential by the voltage drop of the diode D. It has the role of making the transistor Tr ₅ non-conductive when it is in the state.

Therefore, when the power supply voltage E ₁ is lower than the Zener voltage V _Z of the Zener diode 2, the Zener diode 2 is in a non-conducting state, and the base current i ₂ of the transistor Tr ₂ flows, and the transistor Tr ₂ is in a conducting state, and the transistors Tr ₃ and Tr are in a non-conducting state. ₄ are in a non-conducting state, and no voltage is applied to the series circuit of the coil 5 of the magnetic retention type relay 3 and the capacitor _C2 . When the power supply voltage _E1 exceeds the Zener voltage _VZ , the Zener diode 2 becomes conductive, and the Schmitt circuit 4
The potential at the connection point a between the resistor R ₁ and the Zener diode 2, which is the input voltage, is _VZ , and the transistor Tr ₂ becomes conductive.

When the transistor Tr ₂ becomes conductive, the base potential of the transistor Tr ₃ becomes lower and lower, and the degree of conduction of the transistor Tr ₂ becomes deeper.

Furthermore, as the power supply voltage E ₁ gradually increases, the current i ₃
(i ₃ = i ₂ + i ₄ ) also increases, and V _Z <V _E +V _BE1 (V _E = i ₃ ×
R ₅ , V _BE1 : Base-emitter voltage of transistor Tr ₂ ), the base current i ₂ stops flowing, transistor Tr ₂ becomes non-conductive, and the base current i ₉ of transistor Tr ₃ starts flowing, transistor Tr ₃ becomes conductive. Therefore, the transistor Tr ₄ , which is a switching element for driving the relay, also becomes conductive, and a voltage is applied to the series circuit 6 of the coil 5 of the magnetic retention type relay 3 and the capacitor C ₂ , and a charging current i ₅ of the capacitor C ₂ flows. . This charging flow
Since the power supply voltage E ₁ of i ₅ is sufficiently high, it exceeds the impressed current i ₀ of the magnetically held relay 3, and the magnetically held relay 3 operates in reverse.

Next, when the power supply voltage E ₁ gradually decreases and becomes less than the Zener voltage V _Z , the Zener diode 2 becomes non-conductive, the base current i ₂ of the transistor Tr ₂ flows, the transistor Tr ₂ becomes conductive, and the transistor Tr ₃ becomes non-conductive. It becomes a non-conducting state. Since the Zener diode 2 is in a non-conducting state, the potential at point a is high, and the transistor Tr ₂ does not become non-conducting in this state. Therefore, the transistor Tr ₄ also becomes non-conductive, the base potential of the transistor Tr ₅ becomes low, the base current i ₆ of the transistor flows, and the transistor becomes conductive, and the charge in the capacitor C ₂ is discharged as a discharge current i ₇ . Therefore, a current in the opposite direction flows through the coil 5 of the magnetic retention type relay 3, and the state is reversed and restored. Therefore, when the power supply voltage _E1 abnormally decreases and becomes lower than the Zener voltage, the magnetic holding type relay 3 recovers and reverses to become the abnormal state display side, thereby eliminating the trouble before it occurs.

The above contents are illustrated in FIG. 5.

FIG. 6 shows another embodiment. The difference from the embodiment shown in FIG. 4 is that the Schmitt circuit 4 in FIG. 4 is replaced with a comparator having hysteresis characteristics. In this circuit, when the (+) input of comparator 7 is higher than the (-) input, the output of comparator 7 is at a high level H.
and the transistor Tr ₂ ' is in a non-conducting state,
When the (+) input of the comparator becomes lower than the (-) input, the output becomes low level L, transistor Tr ₂ ' becomes conductive, the potential at point C rises, and the resistance
Since it is fed back to the (-) input of comparator 7 via R ₆ ', the voltage at the (-) input becomes higher and higher, and the inversion of comparator 7 has hysteresis characteristics and has fast-on and fast-off characteristics. .

In the explanations of FIGS. 4 and 5 so far, there is a control input Si derived from the output of a security sensor or a sensor for detecting temperature and illumination, for example, and a switching element Tr ₁ that connects the voltage detection means to the power source.
The explanation was for the case where is in a conductive state, but
Naturally, when the control input Si is not present, the Zener diode 2 is in a non-conducting state, and the transistor
Tr ₂ remains conductive and therefore transistor Tr ₄ remains non-conductive.

If the control input Si gradually increases here,
For example, when the output of a temperature detection sensor is used as the control input Si, the temperature gradually changes, so the control input Si gradually changes. Even in cases where the control input Si gradually changes like this, it is equipped with quick-on, quick-break circuits such as Zener diodes and Schmitt circuits.
Since the switching element for driving the relay is turned on and off extremely quickly, there is no possibility of a constant charging current or a constant discharging current as shown in FIG.

As described above, according to the present invention, as a specific invention, a capacitor is connected in series to the coil of a magnetic retention type relay, and the magnetic retention type relay is operated in reverse by the charging current of the capacitor that flows when a voltage is applied to this series circuit. , a relay drive circuit for inverting and restoring the magnetic retention type relay by a discharge current flowing when discharging the charge of the capacitor, comprising a voltage detection means for detecting whether the power supply voltage is equal to or higher than a predetermined value; If the power supply voltage is less than the predetermined value, the relay drive switching element is rendered non-conductive; if the power supply voltage is equal to or higher than a predetermined value, the relay drive switching element is rendered conductive, and the power supply voltage changes from a predetermined value or more to a predetermined value or less. a quick-on, quick-break circuit such as a Schmitt circuit that connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetic retention type relay so as to reverse the switching element for driving the relay to a non-conducting state when the switching element for driving the relay is turned off; Since the relay drive circuit is characterized in that it includes a switching element that discharges the electric charge charged in the capacitor when the switching element is reversed from a conductive state to a non-conductive state, a relay drive circuit with low power consumption can be obtained. At the same time, there is no fear that the magnetic retention type relay will reverse even if there is a gradual change in the power supply voltage E1, and it will not be difficult to connect the power supply voltage or In addition to not causing any inconvenience when the battery voltage decreases, as a combined invention, a capacitor is connected in series to the coil of a magnetically holding type relay, and when a voltage is applied to this series circuit, a charging current of the capacitor flows to charge the magnetically holding type relay. In a relay drive circuit that reverses and restores the magnetic retention type relay by a discharge current that flows when discharging the charge in the capacitor,
A voltage detection means for detecting whether the power supply voltage is above a predetermined value, a switching element for connecting the voltage detection means to the power supply by another control input, and a switching element for driving the relay if the power supply voltage is below the predetermined value. is rendered non-conductive, the relay driving switching element is rendered conductive when the power supply voltage becomes a predetermined value or more, and the relay driving switching element is rendered conductive when the power supply voltage changes from a predetermined value or more to a predetermined value or less. A quick-on, quick-break circuit such as a Schmidt circuit that connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetically held relay so as to reverse the state to a conductive state, and a switching element for driving the relay to change from a conductive state to a non-conductive state. Since the relay drive circuit is characterized by including a switching element that discharges the electric charge charged in the capacitor when reversed, there is no fear that the magnetically held relay will not reverse even if the control input changes slowly. It is extremely effective.

[Brief explanation of drawings]

The drawings are diagrams for explaining the drive circuit of the relay of the present invention, and FIG. 1 is a conventional relay drive circuit diagram, and FIG.
The figure is a waveform diagram of the charging current i1 in Figure ₁ , and Figure 3 is the charging current when the power supply voltage changes slowly.
The current waveform diagram of i ₁ ′ is shown. FIG. 4 is a circuit diagram showing a first embodiment of the present invention, FIG. 5 is a voltage waveform diagram of the embodiment of FIG. 4, and FIG. 6 is a diagram of a second embodiment. 1: Voltage detection means, 2: Zener diode,
4: Schmitt circuit, 5: coil of magnetic holding type relay 3.

Claims (1)

[Claims] 1. A capacitor is connected in series to the coil of a magnetic retention type relay, and when a voltage is applied to this series circuit, the charging current of the capacitor causes the magnetic retention type relay to operate in reverse, and the capacitor is activated. A relay drive circuit that reverses and restores the magnetic retention type relay by a discharge current that flows when discharging a charged charge, comprising a voltage detection means for detecting whether a power supply voltage is above a predetermined value, and a voltage detection means for detecting whether the power supply voltage is below a predetermined value. For example, the switching element for driving the relay is made non-conductive, and when the power supply voltage reaches a predetermined value or more, the switching element for driving the relay is made conductive, and when the power supply voltage changes from a predetermined value or more to a predetermined value or less, the relay A quick-on, quick-break circuit such as a Schmitt circuit that connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetically held relay so as to reverse the driving switching element to a non-conducting state, and the relay driving switching element are brought into conduction. A switching element that discharges the electric charge stored in the capacitor when the state is reversed from a non-conducting state to a non-conducting state. 2. When a capacitor is connected in series to the coil of a magnetic retention type relay, and the charging current of the capacitor that flows when a voltage is applied to this series circuit causes the magnetic retention type relay to operate in reverse, and the charge in the capacitor is discharged. In a relay drive circuit that reverses and restores the magnetic retention type relay by a flowing discharge current, the voltage detection means detects whether the power supply voltage is equal to or higher than a predetermined value, and the switching means connects the voltage detection means to the power supply by another control input. If the power supply voltage is below a predetermined value, the relay driving switching element is brought into a non-conducting state, and if the power supply voltage is above a predetermined value, the relay driving switching element is brought into a conductive state. A quick input circuit such as a Schmitt circuit connects the power supply voltage to a series circuit of a coil and a capacitor of the magnetic holding type relay so as to reverse the relay driving switching element to a non-conducting state when the voltage changes from above a value to below a predetermined value. a fast-acting circuit;
A relay drive circuit comprising: a switching element that discharges the charge stored in the capacitor when the relay drive switching element is reversed from a conductive state to a non-conductive state.