JPH0427073Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a relay circuit, particularly a relay circuit that is installed between a DC power source and a load such as an amplifier supplied with power from the DC power source, and switches the supply of power to the load by opening and closing. It is.

A conventional circuit of this type is shown in FIG. In the figure, 1 is an input terminal into which a relay switching control signal is input, 2 is a base connected to input terminal 1,
Emitsuta is grounded, and collector is relay 3
4 is an amplifier that is supplied with power from the DC power source E via the relay switch 3b of the relay 3, and 5 is the power supply for the amplifier 4. A power decoupling capacitor is connected between the end and the ground, and 6 is a surge absorption diode.

By the way, if the load amplifier 4 is connected in multiple stages and each stage is supplied with power from a common power source, slight fluctuations caused by the final stage will be prevented by the common impedance. As a result, motor voting, which is ultra-low frequency oscillation of about 0.05 to 80Hz, occurs. Therefore, in order to avoid this mutual interference, a decoupling circuit consisting of, for example, a CR circuit is provided in the power supply path between the stages. The power supply decoupling capacitor 5 is provided precisely for this purpose.

The above-mentioned relay circuit is used as an input when inspecting a printed circuit board circuit unit configured by mounting various integrated circuits (ICs) on a single printed circuit board together with the amplifier 4 and decoupling capacitor 5. Applying a control signal to the terminal 1 turns on the transistor 2 and operates the relay 3, which is actually used to supply power to the amplifier 4 by closing the relay switch 3b, and is used for the measurement and testing equipment of the circuit unit. constitute a part. Since the circuit units that have been inspected have not yet been actually assembled into the housing, they are stacked one after another. The charge is
Accidents often occurred in which ICs in circuit units were destroyed due to electrical discharge caused by contact between printed patterns of circuit units.

The present invention was developed in order to solve the above-mentioned conventional problems, and its purpose is to prevent the decoupling capacitor from remaining charged at the end of the inspection. It is an object of the present invention to provide a relay circuit that prevents accidents caused by discharge of charges stored in this decoupling capacitor.

The present invention will be explained below with reference to FIG. 2 of the drawings. FIG. 2 shows an embodiment of the present invention, and parts equivalent to those in FIG. 1 are given the same reference numerals. In the figure, the relay switch 3b' of the relay 3' differs from the normally open relay switch 3b in FIG. When the relay coil 3a' is not energized, the movable contact A comes into contact with the fixed contact B, and when the relay coil 3a' is energized, the movable contact A comes into contact with the fixed contact C. It works like that. The movable contact A is connected to the amplifier 4 and the decoupling capacitor 5, and the fixed contacts B and C are connected to the ground and the + side of the DC power source E, respectively.

With the above configuration, one end of the decoupling capacitor 5 is connected to the ground through the movable contact A and the fixed contact B at all times when the relay 3' is not working. Therefore, even if the relay 3' is activated during inspection of the circuit unit, the relay switch 3b' is switched to the side opposite to that shown in the figure, and the decoupling capacitor 5 is charged from the DC power supply E through the relay switch 3', When the test is completed, relay 3' is no longer activated and relay switch 3b' returns to the state shown, capacitor 5
The electric charge that had been stored in the relay switch 3b' is now discharged to the ground through the relay switch 3b'. As a result,
Even if a large number of inspected circuit units are stacked one on top of the other and the patterns of the units come into contact with each other, accidents such as destruction of the IC due to discharge will not occur.

As described above, according to the present invention, when the relay switch of the relay included in the relay circuit is switched to the power cutoff side, the decoupling capacitor is charged because it is provided with a contact that connects the decoupling capacitor to the ground. This prevents the IC from being left unattended, and the IC, etc., from being destroyed by the discharge of the charge in the decoupling capacitor, as was the case in the past.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional relay circuit, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 3'...Relay, 3b...Relay switch, 4
...Amplifier, 5...Decoupling capacitor,
E...DC power supply, B...Fixed contact.

Claims (1)

[Claim for Utility Model Registration] In response to the energization of the relay coil by the relay switching control signal input to the input terminal, the movable contact of the relay switch is brought into contact with the fixed contact connected to the DC power supply, An integrated circuit mounted on a printed circuit board with a decoupling capacitor,
A relay circuit that supplies DC power to a load such as an amplifier, wherein the relay switch is connected to a second circuit connected to ground.
The movable contact is configured to contact the second fixed contact when a relay switching control signal is not input to the input terminal and the relay coil is not energized, and the movable contact is configured to contact the second fixed contact, and A relay circuit characterized in that a discharge path for discharging the charge of the decoupling capacitor charged by power supply is formed through the movable contact and the second fixed contact.