Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1986-12-16
1988-08-02
Heyman, John S.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
307471, 307475, 307236, 307360, 3075421, H03K 1921, H03K 19092, H03K 500
Patent
active
047615664
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a circuit for converting an interface signal from a controlled system into a voltage signal, and more particularly to an input circuit by which an interface signal provided in the form of a contact signal or a signal equivalent thereto is converted into a voltage signal.
Various types of input circuits are employed for converting an interface signal from a controlled system into a voltage signal. The simplest and cheapest way is a voltage input circuit as shown in FIG. 1.
In the voltage input circuit depicted in FIG. 1, an input signal is applied to a filter circuit 1 to remove a noise component, and is then compared with a reference voltage Vref in a comparator 2, which yields a voltage signal output when the input signal is higher than a fixed level.
On the other hand, an interface signal between a machine tool and a numerical controller or programmable controller is, in general, not a voltage signal but a contact signal or non-contact signal equivalent thereto which is produced by a semiconductor element is, a signal resulting from an ON/OFF operation. Accordingly, in order to read out such a contact signal and derive therefrom a voltage signal output, an input circuit is needed which is provided with a circuit for converting the contact signal into a voltage signal.
With such an input circuit, when the interface signal is the above-mentioned contact signal, it is necessary to produce a voltage signal whose polarity always changes in the same a manner in response to the turning ON and OFF of the contact, irrespective of the arrangement of the contact signal generating circuit. Further, it is demanded that the input circuit be as simple in structure as possible even if many contact signal generating circuits are employed.
Heretofore, such an input circuit as depicted in FIG. 2 has been used for converting the above-said contact signal into a voltage signal output. In FIGS. 2A and 2B, reference numeral 3 indicates generally a converting circuit, 4 a resistor, 5 a contact, .circle.1 a power source terminal, .circle.3 a signal terminal, .circle.2 a terminal connected to one end of the resistor 4 connected at the other end to the signal terminal .circle.3 , and .circle.4 a grounding terminal. The signal terminal .circle.3 is connected to the input side of the input circuit shown in FIG. 1.
There are two kinds of methods for connecting the contact to the converting circuit shown in FIGS. 2A and 2B; one is to ground the contact at one end thereof and the other is to connect the contact at one end to the power source. FIG. 2A shows the connection of one end of the contact to the grounding terminal .circle.4 , in which case the terminals .circle.1 and .circle.2 are short-circuited and the contact 5 is connected between the terminals .circle.3 and .circle.4 . FIG. 2B shows the connection of the contact 5 to the power source terminal .circle.1 in which case the contact 5 is connected between the terminals .circle.1 and .circle.3 and the terminals .circle.2 and .circle.4 are short-circuited. Usually, these two kinds of connections are selectively employed in accordance with the safety standards adopted and the contact connecting position on the side of the machine tool.
With the input circuit shown in FIGS. 2A and 2B, the polarity of the voltage signal output resulting from the turning ON or OFF of the contact 5 differs with the methods of conenction depicted in FIGS. 2A and 2B.
Accordingly, the convetional input circuit presents the problem that the sign of the input signal, which is applied to an internal control logic of the numerical controller or programmable controller in response to the ON/OFF operation of the contact, differs depending upon which of the abovementioned methods of connection is employed.
SUMMARY OF THE INVENTION
To solve the above problem, the input circuit of the present invention basically has such a arrangement as shown in FIG. 3. Reference numeral 101 indicates the same input circuit as depicted in FIGS. 2A and 2B, which cir
REFERENCES:
patent: 3478314 (1969-11-01), Wedmore
patent: 4068138 (1978-01-01), Miyakawa et al.
patent: 4461961 (1984-07-01), Kendall
patent: 4630215 (1986-12-01), Graham
Inoue Michiya
Satoh Jun-ichi
Fanuc Ltd
Heyman John S.
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