JPS6025320A - Transistor contact circuit - Google Patents

Abstract

PURPOSE:To constitute a break contact by transistors (TRs) by connecting a resistor between the base and collector of paired TRs of Darlington connection, grounding the emitter and applying a control signal to the base. CONSTITUTION:TRs 12, 13 are connected in the form of Darlington, the emitter of the TR13 is grounded and the collector connected in common is connected to a load 5. A resistor 14 is connected between the base and collector of the TR12 and an output of a TR driving circuit 7 is applied to the base. When the output of the TR drive circuit 7 is opened, a base current flows via the resistor 14 to turn off both the TRs 12, 13. When the output of the TR driving circuit 7 is grounded, the TRs 12, 13 are both turned off. Thus, the break contact is formed by TRs and miniaturization, low power consumption and high speed are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transistor contact circuit), particularly a transistor that functions as a break contact of a relay (a relay contact that closes when the relay drive power is turned off) and sends out earth air. This relates to contact circuits.

Conventionally, a circuit using the break contact of the relay has generally been used for the 8R line, power supply alarm output contact, etc. of the carrier terminal equipment. This is because, on the external interface, if the device power supply including the relay drive power supply is cut off, the relay contacts must be closed to send out the ground air.

An example of a conventional ground air sending circuit using this type of relay is shown in the first example.
To illustrate and explain, in the figure, 1 is a relay drive circuit, 2 is an apparatus power supply including a relay drive power supply that supplies power to this relay drive circuit 1, 3 is a relay driven by the output of the relay drive circuit 1, and 4 is a relay drive circuit. is the contact point of this relay 3, 5
is a load connected to this relay contact 4 via an interface, and 6 is a load power supply connected to this load 5.

In the earth contact sending circuit configured in this way, the relay 3 is constantly operated by the relay drive circuit 1.
'% 1 - The quantile has a break as shown by the broken line. Then, at the time of a signal or when the device power source 2 is cut off, the relay 3 is inactivated and its break contact is closed, thereby making it possible to send earth air to the load 5 side.

However, in earth air sending contact circuits using relays, a mechanical component called a relay is used, so there is a drawback that miniaturization cannot be achieved, and chattering occurs, making it difficult to operate at high speeds. There were drawbacks such as the transmission information being distorted due to the inability to perform switching operations, and the need for electric power to drive the relays. Another disadvantage is that the device has a short lifespan due to worn parts such as mechanical contacts.

In order to solve this problem, there is a method of converting the relay circuit into a multilayer circuit and using an open collector transistor. An example thereof is shown in FIG. 2 and will be explained.

In FIG. 2, the same reference numerals as in FIG. 1 indicate corresponding parts; 7 is a transistor drive circuit that controls the base potential of transistor 8; 9 is a relay that detects a power failure;
10 is a contact point of this relay 9. The emitter of the transistor 8 is grounded, the collector is connected to the C load 5 via the interface, and the power failure detection relay 9
The base is connected to the output terminal of the transistor drive circuit 7 via a resistor 11.

In the circuit configured in this way, the transistor drive circuit 7 is controlled depending on the presence or absence of an input signal.

Power is input to the base of transistor 8. When the transistor drive circuit 1 is operating, the transistor 8 is switched on and off, but when the device power supply 2 is cut off, the power supply that biases the base of the transistor 8 is turned off. As a result, the transistor 8 becomes non-conductive, that is, becomes open. Therefore, a power failure detection relay 8 is provided separately from the transistor 8, and the collector of the transistor 8 is connected to the ground via a relay contact 10.

However, with such means, chattering and distortion of transmitted information are improved because the normal operation is a transistor contact, but a relay is required to save the transistor 8, which becomes open when the power is cut off. However, it has disadvantages in that it cannot be miniaturized and requires electricity. Another drawback is that the lifespan of the device is shortened due to the wear of mechanical contacts such as relays.

The present invention has been made in view of the above points VC, v1i, in order to solve such problems and eliminate such drawbacks.
The purpose is to eliminate wear parts such as all-thermal mechanical contacts, to achieve miniaturization and low IR power consumption, to prevent chuckling that is unique to relay contacts, and to perform high-speed switching #1 operation. The purpose of the present invention is to provide a transistor contact circuit that can perform the following steps.

To achieve this purpose, the collectors of the first and second transistors are connected in common, the emitter of the first transistor is connected to the base of the second transistor, and a connection is made between the base and collector of the first transistor. A resistor is connected to the second transistor, and the emitter of the second transistor is grounded.
When earth is applied to the base of the transistor, both the first and second transistors are in an open state, and when the base of the first transistor is in an open state, both the first and second transistors are in an open state. It is designed so that air can be sent to the ground when it is in the on state.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 3 is a circuit diagram showing an embodiment of a transistor contact circuit according to the present invention.

In FIG. 3, the same parts as in FIGS. 1 and 2 are designated by the same reference numerals, and their explanation will be omitted.

12.13 is a Darlington connected transistor,
The emitter of this transistor 13 is grounded, and the commonly connected collector is connected to the load 5 via an interface, and is also connected to the base of the transistor 12 via a resistor 14, and the base of this transistor 12 has its base potential. A terminal connected to the output terminal of the transistor driving circuit 7 to be controlled is connected to the base of the transistor 130.

Next, the operation of the embodiment shown in FIG. 3 will be explained.

mass, the collector of transistor 12.13 is the load power supply 6
When the output of the transistor drive circuit 7 is biased with the negative terminal (minus power supply) on the side and the output of the transistor drive circuit 7 is open, a base current flows through the resistor 14, and this base current increases.
li, transistors 12 and 13 both turn on. Then, when the transistor 13 is turned on, earth air is sent to the load 5 side via the interface.

Next, when the output of the transistor drive circuit 7 becomes low, the base potential of the transistor 12 becomes OV, and both transistors/transistors 12 and 13 turn off. Here, since the transistors 12 and 13 are Darlington-connected as described above, the current amplification factor is large;
The resistance value of the resistor 14 can be made sufficiently large in the field, and the load 5 side becomes almost open.

Next, when the device power supply 2 is cut off, the output of the transistor drive circuit 7 becomes open, so the base of the transistor 12 is biased to the load side negative power supply by the load power supply 6 through the entire resistor 14. Transistor 12.
13 both transition to the on state. Then, when the transistor 13 is turned on, earth air is sent to the load 5 side via the interface.

In this way, when the device power supply 2 is normal, the open collector transistor contact switches on and off according to the input signal, and when the device power supply 2 is cut off, the transistor contact closes. In other words, it can perform the same operation as a relay break contact.

As explained above, according to the present invention, by configuring the break contact of a relay with a transistor contact, it is possible to achieve miniaturization and lower power consumption, and to prevent chuckling that is inherent to relay contacts. Since it is possible to perform high-speed switching operations, the practical effects are extremely large. Furthermore, since no thermomechanical contacts are required, there are no wear parts, which is extremely effective in that the life of the entire device can be significantly extended and it can be provided at low cost.

[Brief explanation of drawings]

FIGS. 1 and 2 are circuit diagrams showing examples of conventional earth air detection contact circuits, and FIG. 3 is a circuit diagram showing an embodiment of a transistor contact circuit according to the present invention.

Claims (1)

[Claims] the collectors of the first transistor and the second transistor are connected to each other; the emitter of the first transistor is connected to the base of the second transistor;
Connect a resistor between the base and collector of the transistor,
The emitter of the second transistor is grounded, and when earth is applied to the base of the first transistor, both the first and second transistors are in an open state; 1. A transistor contact circuit characterized in that the first and second transistors are turned on when the bases of the transistors are opened, thereby allowing air to be sent to the ground.