JPS6097724A - Contact signal input circuit - Google Patents

Abstract

PURPOSE:To output a sense voltage having a large width of change by using a mutual inductance, two switches and a capacitor so as to use the same low voltage power supply as that of the succeeding logical circuits. CONSTITUTION:In operating complementarily the 1st switches SW101, SW102 and the 2nd switches SW201, SW202, a current is injected to the primary winding of the mutual inductance and a current is regenerated from the primary winding L1 to the power source via the 2nd switches. This regenerating current is branched also to the secondary winding so as to charge a capacitor C1. When a contact Sin is turned off and the current is regenerated, since a power supply E3 is connected via a diode D3 or the like, a voltage higher than the power supply voltage is generated to the anode of the diode D3. When the contact Sin is closed and the current is regenerated, the current flows only to the secondary winding L2, a voltage generated in the secondary winding is transferred to the primary winding, this voltage is given as a value via the diode D2 or the like and a zero voltage is given to the capactior C2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an input circuit for inputting contact signals to a sequence control device or the like. To explain in more detail, 5VD
A sense current for sensing the contact signal is supplied to each horn end using a low voltage power supply such as C, and the contact signal A/
The present invention relates to a contact signal input circuit that is capable of transmitting a /j sense voltage signal of sufficient magnitude, such as 015 VDC, to a subsequent digital logic circuit in relation to an off state.

<Prior Art> FIG. 1 is a four-circuit diagram showing an example of a conventional contact signal input circuit. In this figure, 1.2 are input terminals, and 3-inch contacts are connected to these terminals, while lines W + , W
2 are connected. The line WI is connected to a low voltage power source E1 of, for example, 5V, which is the same as the power source that powers the logic circuit connected to the subsequent stage of this circuit, through a current limiting resistor R0 for supplying a sense current. The line W2 is a common line. R+ and C+ are a resistor and a capacitor C which constitute a time constant circuit for supplying a cleaning current to the contact S in. The diode D1 inserted in the line W1 is a current backflow prevention diode A to prevent the current from flowing into the circuit when the connection 113in is operating the load of an external pond. It is. B2 is connected to line 1- in order to cancel the forward voltage of quad A-D+.
This is a compensation diode inserted at 1. R2 is a receiving resistor, C2 is a capacitor for smoothing the jitter component of the contact input horn signal, and B1 is a buffer amplifier that amplifies the voltage across the receiving resistor R2 and outputs it to the subsequent logic circuit.
V low voltage power supply "2" is added as a power supply.

In this case, the circuit constants are determined as shown in FIG. 1, and the operation is as shown in FIG. 2 for the 3-inch contact A.DELTA.) operation. In Figure 2, figure (a) shows the operating state of the 3-inch J air connection, and figure (b) shows the voltage e across the capacitor C1.
cl, Figure (C) shows the state of the current 11 flowing in response to the A/A operation of the contact Sin, and Figure (d) shows the state of the voltage e and C2 of the buffer amplifier B1.1 Waveform diagram It is.

Buff? For example, when the amplifier 13 blind is configured with C-MO8 logic elements, it would be ideal if the input terminal is 5V for 1 and the input voltage is O for the O level value, but in reality In the contact signal input circuit, the level tends to fall, and the 0 level tends to rise.This is because the resistance of the 3-inch contact wire increases the O level, and the drop in insulation at the 3-inch contact causes the level to fall. .

<Disadvantages of the prior art> In the case of the J conventional circuit shown in Figure 1, the Lebel value is 4V, and the level value is 0.75V, as shown in Figure 2(d), and the threshold margin of the Lebel and 0 levels is It had the disadvantage of lowering the

Simply turn the power supply E to 5 to increase the voltage of the level.
If you just raise it from ■ to 6V, you can improve the Lebel threshold margin, but the O level voltage is 0.7V.
As the voltage increases from 5 V to 1.4 V, the O level threshold margin decreases.

It is possible to choose the power source E1 higher than the power source [2 and add a diode Do, but this would require a different type of power source, and that would increase the no.

<Purpose> The first object of the present invention is to provide a contact that can output a sense voltage with a small variation range while using a voltage power supply, which is the same as the power supply that connects the logic circuit connected to the subsequent stage of the tree diagram WB. The purpose is to realize a signal input circuit.

<Configuration of the Invention> The configuration of the present invention includes a mutual inductance means having a primary winding and a secondary winding, and a first inductor which connects the primary winding to a power source with a first polarity and injects current. a second switch connected to the power supply at the second pole 11 of the secondary winding, a contact connected to the input terminal of the secondary winding; The receiving resistor connected to the line and the stage [
], the same lit voltage power supply as the power supply that energizes the logic circuit connected to the latter stage of this circuit is used as the power supply, and the sense current for sensing the contact signal is supplied to the above during the current discharge period of the primary winding. The voltage is applied to the secondary winding side, and the voltage across the secondary winding according to the state of the contact is transmitted to the primary winding, and the receiving resistor generates a sense voltage of the contact signal. It is.

<Example> FIG. 3 is a circuit diagram showing an embodiment of the present invention.

In this figure, elements that are substantially the same as those in FIG. 2 are designated by the same reference numerals, and their explanations are omitted. 11 is a transformer with phase n inductance means and -C, which is composed of a primary winding + and a secondary winding L2, and the winding ratio of the primary and secondary windings is 1:1.
A simple separation type is used.

Switch 3 connected to power source E1 and current limiting resistor R9
W 101, and a switch S W 102 connected to the common and one end of the primary winding L+ via a diode D3.
constitutes a first switch for injecting current into the primary winding 11 with a first polarity. Note that the diode D3 is inserted to limit the direction of current flowing to the primary winding.

common, switch SW 101 and current limiting resistor R
The switch 5W201 connected to the connection point with O, and the switch 5W202 connected between the 5V low voltage power supply E3 and the connection point with the switch 5W202 are primary reverse wires. ! A second switch is configured to connect the power supply with a second polarity to the second polarity and discharge current.

Is the first switch of the Omu in phase with the second switch? il
After repeated operations M, current is injected into the primary winding (-1) through the first switch, and current is returned from the primary winding L1 to the power source through the second switch. This reduced current is also shunted to the secondary winding L2 and charges the capacitor C+, but when the voltage across this capacitor reaches the power supply voltage of the primary winding L2, the secondary winding L2
No energy injection occurs and the reduction current flows only through the primary winding L1.

When the contact 3in is in the Δ) state, one, and when the current is returned, the 5■ power supply E3 is the diode D, ll! Since it is connected through I, a voltage higher than the power supply voltage of 5■ is generated on the anode side of the diode D3. By charging the peak rUi pressure at this time, the voltage eC2 of the capacitor C2 is maintained at 5.

-n % Contact 3 i n is in the A state and at the time of current return, the impedance of the transformer [+0 secondary side is low, and the current flows only through the secondary winding L2. This current causes 2
The voltage developed in the secondary winding is copied to the primary winding [1, and this voltage is transferred to the diode D211! ! The VD voltage is transmitted to the capacitor C2.

FIG. 4 is a circuit diagram of an embodiment in which a plurality of contact signal input circuits are energized by a set of switches.

In this figure, elements that are substantially the same as those in FIGS. 1 and 3 are designated by the same reference numerals.

5W101' and 5W102' are 1-transistors constituting the first switch. For example, 250K l-I
A Z switching signal is added. 5W201
', 5W202' are diodes constituting the second switch.

When the constants are determined as shown in the figure, the operation is as shown in the waveform diagram of FIG. 5. In Figure 5 - Figure C (a)
Figure (b) shows the operating status of the 3 inch contact, and Figure (b) shows the operating status of the 3 inch contact.
1. , Figure (C) shows the state of current 1 [+ flowing through +, 2
Figure (d) is a waveform diagram showing the state of the current IL2 flowing through the second valley line L2, depending on the state of the first switch.

When contact 3 in is in Af, the reduction of ffR current occurs between Ta and current limiting resistor Ro and quasiode 5.
W201' At which connection point is the "mongara die A-l"
'5W201' ノJ: Subtract 0.5v for 7 minutes Ita, -O,! iV's electric shock "" occurs, and
1 on the anode side of 2. L, 1-5■ power supply E3
A voltage e'2 is generated by adding the drop caused by the two diodes 3W202' and D3, and the diode 5W202'
At the connection point between 02' and diode D3, there is an rri source E3.
+5.5V voltage ef, which is the sum of the diode drop of diode 5W201', is the light 'U! Jru. Capacitor "j' C2 is JzzC at the peak voltage at this time.
When charged, the voltage ec2 across the two terminals is 5V.
is maintained.

The first J contact Si n is A, and the reduction current is 1!
do. At this time, there are 0 at both ends of the secondary volume IIL-2.
．． 75 V (Tie; t t'D+ (7) 0.5 Vk:, 100 J-m of resistance R+ with an average current of 2.
A voltage (plus the drop caused by the 5mA flowing) is generated, and this is copied to the primary winding. Kono 0,75 V hub T: Nkara'j IA-to 5W2
01'.

Since the value is transmitted to the capacitor C2 via the two diode drops of D2, the capacitor 4J-02
A single port voltage is transmitted to the terminal.

<Effects> According to the present invention, by effectively utilizing the mutual inductance means, it is possible to generate a voltage lower than the power supply voltage using the same low voltage power supply that energizes the subsequent logic circuit. A sense voltage IE with a sufficient threshold margin can be obtained for any of the output, level, and O levels.

Furthermore, since the insulating element by the mutual inductance means is added to the circuit, it is not affected by the common potential difference inside and outside the device, and has a high resistance L.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an example of the curved shape of a conventional contact signal input circuit, Fig. 2 is a waveform diagram for explaining the operation of the conventional circuit based on Fig. 1, and Fig. 3 is a circuit diagram showing an example of the shape of a conventional contact signal input circuit. A circuit diagram showing an example, FIG. 4 is a circuit diagram showing another embodiment of the present invention, and FIG. 5 is a waveform diagram to explain the operation of the embodiment circuit of the present invention shown in FIG. It is. 11... Mutual inductance means, 1-1... Primary winding, 1-2... Secondary winding, 5W101, 5W10
2, 5W101', 5W102'...Switch for purchasing the first switch, 5W201, 5
W202, 5W201'. 5W202'...Switch constituting the second switch, 3 in =...Contact, R2...Receiving resistor,
E+, R2. R3...Similar low-voltage F1 power supply.

Claims (1)

[Claims] a first switch for connecting the primary winding to a power supply with a first polarity to inject current; a second switch for connecting the winding to the power supply with a second polarity and discharging current; a contact connected to the input terminal of the secondary winding;
It has a receiving resistor connected to the primary winding that senses the state of the contact, and uses the same low voltage power source as the power source that energizes the logic circuit connected at the later stage of this circuit as the power source. 6 [! to the secondary winding side, transmitting the voltage across the secondary winding according to the state of the contact to the primary winding, and generating a sense electrician of the contact signal from the receiving resistor. contact signal input circuit.