JPS6016022Y2 - Latching relay drive circuit - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a latching relay drive circuit.

Conventionally, this type of latching relay drive circuit is shown in Fig. 4a.
A voltage V as shown in .

When ' is applied from the control circuit 2' of FIG. 3 to the trigger circuit 1', first the resistor R', the Zener diode zd',
Current flows through the series circuit of resistors R, /, and transistor T1
', T2' become conductive.

As a result, the voltage V□' at the connection point between the resistor R2' and the diode D' of the charge/discharge circuit 3' rises steeply as shown in FIG.

The voltage V□' is connected to a diode D', a capacitor 01',
The voltage is applied to the series circuit of latching relay 4', and capacitor C1' is charged.

At the start of charging the capacitor 01', that is, when the output voltage Vz' of the trigger circuit 1' becomes high, the charging/discharging circuit 3'
A charging current also flows into the junction capacitance between the base and collector of transistor T3' for a short period of time, causing transistor T4 to
′ as a base current.

Furthermore, the base current flows into transistor T5',
It becomes conductive and a current I'' is applied from the output terminal of the trigger circuit 1' to the circuit including the diode D' and the transistors T3'9 T4'9 'r5'.

The current 1// is connected to the diode D' as shown in FIG. 4C.
Charging current 1' flows through the base of transistor T3'.
If the emitters are biased in the opposite direction, it will be stopped, but since there is no limiting resistor in the circuit, there is a risk that the voltage will become excessive even if it is only for a few microseconds, which has the disadvantage of causing destruction of the transistors T,' and an increase in power consumption. Ta.

In other words, the voltage applied to the transistor Tslt originally from the control circuit 2'.

This is to connect the latching relay 4' to the capacitor C□' through conduction when ' is removed, so its current capacity is determined by the power supply voltage of the control circuit 2' and the coil resistance of the latching relay 4'. r (usually several 10c to 100
0Ω), then 1, V ■・.

It is designed to withstand sufficient current.

However, as described above, if the transistor T5' is erroneously turned on by the base-collector capacitance of the transistor T3' when the voltage from the control circuit 2' rises, the collector-emitter of the transistor T5' will be turned on by the base-collector capacitance of the transistor T3'. Since the output terminals are directly connected via the main circuit of the semiconductor switch made up of transistors T1' and T2' and the diode D', the current value becomes an almost perfect resistance. A short circuit occurs.

In reality, it has been confirmed that a current of several amperes flows for a power supply voltage of 12V, and transistors T4' and T5'
In the above-mentioned example, the breakdown withstand capacity is about several hundred milliamperes, so even if the conduction time is several microseconds, the breakdown will occur instantly.

In order to eliminate this drawback, a limiting resistor may be inserted into the collector circuit of the transistor T5', but this would also suppress the discharge current of the capacitor C1', making it impossible to operate the latching relay 4'.

On the other hand, without applying the charging current of the junction capacitance between the base and collector of the transistor L' to the transistor T,
5', but this requires the value of resistor R5' to be small, and when the capacitor 01' is discharged, the base N current of the transistor T,' is insufficient, causing the latching relay 4' to be removed. I can't get it to work.

The present invention aims to provide a latching relay drive circuit that eliminates the above-mentioned drawbacks.

The latching relay drive circuit of the present invention will be explained below with reference to the drawings.

In FIG. 1, a trigger circuit connected to the output end of the 1po control circuit 2 sends out an appropriate output according to the output signal of the control circuit 2. In FIG.

3 is a charging/discharging circuit connected to the output end of the trigger circuit 1, into which a series circuit of a first capacitor C1 and a latching relay 4 is inserted; The latching relay 4 is operated by charging and discharging the first capacitor C□.

T1 is a PNP type first transistor of the trigger circuit 1, and its emitter is connected to one of the output terminals of the control circuit 2.

T2 is a second NPN transistor whose base is connected to the collector of the first transistor T1 and whose collector is connected to the base of the first transistor T1.

R1 is a first resistor, which is inserted between the emitter and base of the first transistor T.

R2 is a second resistor, which is inserted between the base and emitter of the second transistor T2.

zd is a Zener diode inserted between the base of the first transistor T□ and the other output terminal of the control circuit 2.

R3 is a third resistor, and is inserted between the Zener diode zd and the other output terminal of the control circuit 2.

R4 is a fourth resistor, which is inserted between the emitter of the second transistor T2 and the other output terminal of the control circuit 2.

D is a diode of the charging/discharging circuit 3, which is inserted between the emitter of the second transistor T2 and the first capacitor C□.

T3 is a PNP type (7) third transistor, the emitter of which is connected to the connection point between the diode D and the first capacitor C□, and the base connected to the second... Fourth resistor R2
゜Connected to the connection point of R4.

T4 is a PNP type fourth transistor that is Darlington connected to the third transistor T3, and has a collector connected to the emitter of the third transistor T3, and a base connected to the collector of the third transistor T3. There is.

T is the fourth transistor T. A PNP type fifth transistor is Darlington-connected to the latching relay 4, and has a collector connected to the collector of the fourth transistor T4, a base connected to the emitter of the fourth transistor T, and an emitter connected to the latching relay 4. and the control circuit.

R6 is a fifth resistor, which is inserted between the base of the fourth transistor T and the emitter of the fifth transistor T5.

C2 is a second capacitor, which is connected in parallel to the fifth resistor R6.

Thus, an output voltage V having a waveform as shown in FIG. 2a is produced from the output terminal of the control circuit 2.

is applied to the trigger circuit 1, the output voltage V.

reaches a predetermined value, Zener diode 2. becomes conductive, and current flows through the series circuit of the first resistor R□, the Zener diode Zd, and the third resistor vcR3.

As a result, the voltage between the base and emitter of the first transistor T□ becomes 0.6V or more, and the first transistor T1
is conductive.

When the first transistor T1 becomes conductive, the second resistor R2,
Current begins to flow in the series circuit of R4.

As a result, the voltage between the base and emitter of the second transistor T2 becomes 0.6V or more, and the second transistor T2
It also conducts.

After the first transistor T1 is turned on, the second transistor T
The time required for the second resistor R2 to become conductive is very small, and the second resistor R2
The voltage V1 at the connection point between D and diode D rises as shown in FIG.

When the voltage V1 rises, the third transistor T3
A charging current flows through the junction capacitance t between the base and collector of , but this is applied as a charging current to the second capacitor C2 and is not applied to the base of the fourth transistor T4.

Therefore, the fifth transistor T5 does not become conductive and malfunction.

On the other hand, the voltage V□ is also applied to the series circuit of the diode D1, the first capacitor C□, and the latching relay 4, and the first capacitor C1 is provided with a charging/discharging type output □ as shown in FIG. 2d. It will be done.

This charging current causes a voltage drop across the diode D, which reverse biases the base and emitter of the third transistor T3, thereby blocking the charging current to the junction capacitance between the base and collector of the third transistor T3. be done.

When the first capacitor C□ is sufficiently charged, the charging/discharging current decreases as shown in FIG. 2d.

Therefore, the current (2) flowing between the output terminals of the trigger circuit 1 becomes only a leakage current flowing through the fourth low circuit B as shown in FIG. 2C.

During the period when the output voltage V0 of the control circuit 2 is at a high level as shown in FIG.
~T remains in a non-conducting state, and thus the above-mentioned state is maintained.

Next is EV.

decreases to less than a predetermined value, the Zener diode zd becomes non-conductive, and the 11th. Second transistor T□, T2
also becomes non-conductive.

As a result, the voltage V□ rapidly falls as shown in FIG.

Therefore, substantially the charging voltage of the first capacitor C1 is applied across the third to fifth transistors T3 to T connected in Darlington connection.

The voltage at the bottom of the third transistor T3 decreases as the voltage V1 decreases, creating a sufficient voltage difference between the base and emitter, and the third transistor T3 becomes conductive.

When the third transistor L becomes conductive, a sufficiently large base current is applied to the fourth transistor T4, and the fourth transistor T also becomes conductive.

Similarly, the fifth transistor T5 becomes conductive, and the discharge of the first capacitor C□ rapidly progresses, causing a charging/discharging current 11 as shown in FIG. 2d to flow.

This causes the latching relay 4 to operate.

As mentioned above, the latching relay drive circuit of the present invention is
A discharge circuit for a capacitor connected in series with a latching relay is configured with three Darlington-connected first to third transistors, and a charging current to the junction capacitance of the first transistor connected to the Darlington is transferred to the other capacitor. This bypasses the second. Since the third transistor is prevented from malfunctioning, the discharging circuit of the capacitor malfunctions when charging the capacitor starts, causing a large amount of current to flow, which can lead to destruction of the transistor and increase in power consumption. Achieve the desired effect.

[Brief explanation of drawings]

Figure 1 is an embodiment of the present invention, Figure 2 is an explanatory diagram of the same operation, and Figure 3 is an example of the present invention.
The figure shows a conventional example, and FIG. 4 shows an explanatory diagram of the same operation. 1...Trigger circuit, 2...Control circuit,
3... Charge/discharge circuit, 4... Latching relay, C1, C2... Capacitor, D...
...Diode, R~R3...Resistance, T1
~T...transistor, zd...zener diode.

Claims (1)

[Scope of utility model registration request] After the output of the control circuit 2 is waveform-shaped by the trigger circuit 1, it is applied to the charging/discharging circuit 3, and a series circuit of the first capacitor C1 and the latching relay 4 is connected between the output terminals of the charging/discharging circuit 3. In a latching relay drive circuit that causes the latching relay 4 to operate in reverse when the output of the control circuit 2 changes from low level to high level and from high level to low level, one end of the input/output terminal of each circuit are connected in common, and the trigger circuit 1 includes a first... and a first... whose bases are connected to each other's collectors.
A switch circuit including second transistors T□ and T2 is connected between the input and output terminals with the first transistor T1 on the input side, and a series circuit of the first resistor R□, Zener diode Zd, and third resistor R3 is connected between the input and output terminals. connected between the input terminals, both ends of the first resistor R□ are connected between the base and emitter of the first transistor T□, and a second resistor R2 is connected between the base and emitter of the second transistor T2. A fourth resistor R1 is connected between the output terminals, and a diode 5D is inserted between the input and output terminals of the charging/discharging circuit 3.
The fourth terminal is connected in Darlington between the output terminals. Fifth transistor T4. The collector and emitter of the synthetic leather transistor T are connected, the base and emitter of a third transistor T3 are connected to both ends of the diode D, and the emitter and emitter of the third transistor T3 are connected to the synthetic leather. A fifth resistor R5 and a second capacitor C are connected to the collector-base of the fourth transistor T4 on the driver side of the transistors, and are connected between the base of the fourth transistor T4 and the emitter of the fifth transistor T5.
A latching relay drive circuit characterized in that it is formed by connecting a parallel circuit with 2.