JP3494803B2 - Automatic contact cleaning circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal circuit using contacts, and more particularly to prevention of contact failure of contacts.

[0002]

2. Description of the Related Art FIGS. 5 and 6 are circuit configuration diagrams showing a configuration of a conventional contact circuit such as a relay and a switch. In FIG. 5, X1 is a contact, R1 and R3 are resistors for passing a current through the contact 1, C1 and C2 are capacitors for DC cut, and R2.
Is a matching resistor, E is a power supply, G is ground, A is a signal input terminal, and B is a signal output terminal. Further, in FIG.
Reference numeral 1 is a switching contact, R1, R3 and R4 are resistors for passing a current through the switching contact Y1, C3 is a DC cut capacitor,
C is a signal input terminal, and others are the same as those in FIG.

Next, the operation will be described. When the signal current flowing through the contact X1 or the contact Y1 is small and the frequency of use of the contact is low, an oxide insulating film or an insulating film due to other foreign matter is formed on the surface of the contact, resulting in poor contact. Therefore, the resistors R1, R3, R4 and the power supply voltage are selected so that a sufficient cleaning current flows through the contact X1 or Y1 with the circuit configuration as shown in FIGS. Then, the contact failure of the contact is prevented by the arc of the cleaning current generated when the contact is opened and closed.

[0004]

Since the conventional automatic contact cleaning circuit is constructed as described above, the resistances R1, R3 and R4 are made small in order to pass a sufficient current for cleaning the contacts. In addition, it is necessary to increase the power supply voltage of the power supply E, which has a problem of affecting the signal circuit.

The present invention has been made in order to solve the above-mentioned problems, and an automatic contact cleaning for suppressing a contact failure by suppressing an influence on a signal by improving a circuit for supplying a current to the contact. The purpose is to provide a circuit.

[0006]

An automatic contact cleaning circuit according to the invention of claim 1 is provided between a signal input terminal, a signal output terminal, and a signal input terminal and a signal output terminal.
In a signal circuit for transmitting a minute signal, which has a first opening / closing means for energizing / blocking a signal current, a DC power supply, a signal input terminal and a first opening / closing means, and a signal output terminal and a first
And a direct current cutting capacitor provided between the opening and closing means of the first opening and closing means in synchronization with the first opening and closing means,
Open when is open, when the first opening and closing means is closed
A close second switching means, when the first switching means and second switching means are open, the charging capacitor is charged by the DC power supply, a charging capacitor, a first switching means, Forming a closed circuit with the second opening / closing means,
Is connected in parallel with the discharging capacitor that discharges the charging capacitor at the moment when the opening / closing means and the second opening / closing means are closed, and does not affect the signal circuit.
It is installed between the DC power supply and the charging capacitor, which has a large resistance value, and does not affect the signal circuit.
A charging resistor for delaying the charging of the charging capacitor having a resistance value of Kisa, and a charging resistor, a second opening / closing means, a discharging resistor, a first opening / closing means and a matching resistor are connected in series to the DC power supply. It is characterized by being connected to and grounded.

An automatic contact cleaning circuit according to a second aspect of the present invention is the automatic contact cleaning circuit according to the first aspect, which has a plurality of signal input terminals and the first opening / closing means is a switchable signal circuit. , The second opening / closing means is also switchable, and the first opening / closing means and the second opening / closing means have contacts corresponding to a plurality of signal input terminals, and each of them is for DC cutting corresponding to a plurality of signal input terminals. It is characterized by including a capacitor, a discharging capacitor, and a discharging resistor.

An automatic contact cleaning circuit according to a third aspect of the present invention is the automatic contact cleaning circuit according to the first or second aspect, in which a discharge current limiting resistor for limiting a discharge current is connected in series to the charging capacitor. It is characterized by

[0009]

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a circuit configuration diagram of an automatic contact cleaning circuit according to Embodiment 1 of the present invention. In FIG. 1, X1 is a relay contact or switch contact (contact) that is the first opening / closing means, C1 is a DC cut capacitor (DC cut capacitor), R1 is a resistor for charging the capacitor C5, and X2 is a contact. A relay contact or a switch contact (contact), which is the second opening / closing means synchronized with X1, R5 is a resistor (discharge resistor) for discharging the capacitor C4, and C4 is a capacitor C5 for rapidly supplying a current to the contact. A capacitor for discharging (a discharging capacitor), C5 is a capacitor for storing a charge for flowing a cleaning current to a contact (charging capacitor), R2 is a matching resistor, C2 is a DC cutting capacitor (direct current cutting). Capacitor), E is current (DC power supply), G is ground, A is a signal input terminal, and B is a signal output terminal.

When the signal current flowing through the contact X1 is small and the frequency of use of the contact X1 is low, an insulating film such as an oxide film is formed on the surface of the contact, resulting in poor contact. Therefore, in order to prevent this contact failure, a circuit configuration as shown in FIG. 1 is used. At this time, the capacitor C5 is charged while the contacts X1 and X2 are open. Contact X1 and contact X1
At the moment when the contact X2 synchronized with is closed, the capacitor C5 is rapidly discharged through the capacitor C4, and a cleaning current flows through the contacts X1 and X2 to prevent contact failure. Next, when the contacts X1 and X2 are opened, the capacitor C4 is discharged through the resistor R5, the capacitor C5 is charged through the resistor R1, and the cleaning current is returned to the state when the contacts X1 and X2 are closed again. At this time, the values of the resistors R1 and R5 can be increased by charging the capacitor C5 and discharging the capacitor C4 for a while, and it is possible to prevent the signal circuit from being affected.

Embodiment 2. The second embodiment of the present invention will be described below with reference to the drawings. 2 is a circuit configuration diagram of an automatic contact cleaning circuit according to a second embodiment of the present invention. 2 is different from FIG. 1 in that the resistor R6 is connected in series with the capacitor C5.

In the second embodiment, when the discharge current of the capacitor C5 becomes large enough to exceed the capacity of the contacts X1 and X2, a resistor (resistor for limiting discharge current) R6 is connected to limit the current. It is characterized by doing. Other operations are similar to those of the first embodiment.

Embodiment 3. The third embodiment of the present invention will be described below with reference to the drawings. 3 is a circuit configuration diagram of an automatic contact cleaning circuit according to a third embodiment of the present invention. 3 is different from FIG. 1 in that a switching contact Y1 and a switching contact Y2 synchronized with the switching contact Y1 are provided instead of the contacts X1 and X2, and accordingly, a capacitor C3, a resistor R7, a capacitor C6, and an input. That is, the terminal C is added.

In the third embodiment, since each contact in the first embodiment is changed to the switching contact, one of the contacts is closed and the capacitor C 6 is opened on the contact side while the cleaning current is flowing. It is characterized in that a state is prepared in which a cleaning current can be made to flow when discharging through the resistor R7 and then closing. The capacitor C5 is charged through the resistor R1 when the switching contact opens. The capacitor C3 operates similarly to the capacitor C1, and the resistors R7 and C6 operate similarly to the resistors R5 and C4, respectively. Other operations according to Embodiment 1
Is the same as.

Fourth Embodiment Embodiment 4 of the present invention will be described below with reference to the drawings. 4 is a circuit configuration diagram of an automatic contact cleaning circuit according to a fourth embodiment of the present invention. In this embodiment, the resistor R6 is added in series to the capacitor C5 in the third embodiment, and the operation of the resistor R6 is the same as that of the second embodiment.

In the above third and fourth embodiments, the case where the number of signal input terminals is two has been described, but it goes without saying that the invention can be applied to the case of a plurality of signal input terminals.

In each of the above embodiments, the input and output of signals may be reversed.

[0018]

According to the automatic contact cleaning circuit of the first aspect of the present invention, it is possible to supply a sufficient current for cleaning the first switching means of the signal circuit by utilizing the discharge of the capacitor, and the discharging capacitor. It is possible to set the value of the discharge resistance to a large value by taking some time for the discharge of, and it is possible to reduce the influence on the signal. Further, since the resistor for delaying the charging of the charging capacitor is provided between the DC power supply and the charging capacitor, the effect on the signal is further reduced.

The automatic contact cleaning circuit according to the invention of claim 2 has a plurality of signal input terminals, and the same effect as in claim 1 can be obtained even in the case of a signal circuit in which the first opening / closing means is a switching type.

In the automatic contact cleaning circuit according to the third aspect of the present invention, since the discharging current limiting resistor for limiting the discharging current is connected in series to the discharging capacitor, the discharging of the charging capacitor is performed by the first switching means. It can be prevented from becoming larger as the capacity is exceeded.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an automatic contact cleaning circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of an automatic contact cleaning circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of an automatic contact cleaning circuit according to a third embodiment of the present invention.

FIG. 4 is a circuit configuration diagram of an automatic contact cleaning circuit according to a fourth embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a conventional automatic contact cleaning circuit.

FIG. 6 is a circuit configuration diagram of a conventional automatic contact cleaning circuit.

[Explanation of symbols]

X1, X2 contacts, C1, C2, C3 DC cut capacitor, C4, C6 discharge capacitor, C5 charge capacitor, R1 resistor, R5, R7 discharge resistor, Y
1, Y2 switching contact.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01H 1/60 H01T 15/00

Claims (3)

(57) [Claims] 1. A signal for transmitting a minute signal having a signal input terminal, a signal output terminal, and a first opening / closing means which is provided between the signal input terminal and the signal output terminal and which makes and breaks a signal current. In the circuit, a DC power supply, a DC cut capacitor provided between the signal input terminal and the first opening / closing means and between the signal output terminal and the first opening / closing means, and the first opening / closing means. Opening and closing in synchronization with the first opening and closing
Open when the means is open and the first opening and closing means is closed
A second opening / closing means which is closed when the first opening / closing means is open, a charging capacitor charged by the DC power supply when the first opening / closing means and the second opening / closing means are open, and the charging capacitor, A discharge capacitor that forms a closed circuit together with the first opening / closing means and the second opening / closing means, and discharges the charging capacitor at the moment when the first opening / closing means and the second opening / closing means are closed; The signal circuit connected in parallel to the discharging capacitor
And a discharge resistor having a resistance value of a size that does not affect, and provided between the DC power supply and the charging capacitor,
A charging resistor that delays charging of the charging capacitor having a resistance value that does not affect the signal circuit , wherein the DC power source includes the charging resistor, the second opening / closing means, and the discharging resistor. An automatic contact cleaning circuit is characterized in that a first switching means and a matching resistor are connected in series and grounded. 2. A signal circuit having a plurality of signal input terminals, wherein the first opening / closing means is a switchable type, the second opening / closing means is also a switchable type, and the first opening / closing means and the second opening / closing means are 2. A direct current cut capacitor, a discharge capacitor, and a discharge resistor corresponding to the plurality of signal input terminals, respectively, having contacts corresponding to the plurality of signal input terminals. Automatic contact cleaning circuit. 3. The automatic contact cleaning circuit according to claim 1, wherein a discharge current limiting resistor for limiting a discharge current is connected in series to the charging capacitor.