Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Amplitude control
Reexamination Certificate
1998-11-25
2001-01-30
Kim, Jung Ho (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Amplitude control
C326S038000, C326S063000
Reexamination Certificate
active
06181189
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to interface circuits provided with functions for dealing with contact inputs and input signals such as logic.
2. Description of the Related Art
There are two methods for inputting input signals to the terminals of control devices composed of microcomputers; these are sink input and source input. In Japan, control devices are mostly of sink input type but overseas, and particularly in Europe, the majority are of source input type. Therefore, makers who produce this type of control equipment have been producing respective control devices for sink input and control devices for source input, and shipping them according to the users' demands. As against this, the makers have recently been trying to reduce the number of types of production machine. For this reason they have been trying to produce control devices composed to be capable of using either of the above two input methods (shared use).
An example of a control device of a composition capable of shared use of the above two input methods is shown in FIG.
1
. This
FIG. 1
is an electrical circuit diagram showing the input circuit part of the control device. As shown in
FIG. 1
, four diodes
2
,
3
,
4
and
5
, resistor
6
and photodiode
7
a
of photocoupler
7
are connected to input terminal
1
. Photodetector
7
b
of photocoupler
7
is connected between a, for example, 5V DC voltage terminal Vp
5
and earth. Moreover, the junction point between photodectector
7
b
and DC voltage terminal Vp
5
is connected to input terminal
8
a
of microcomputer
8
.
Contacts
10
a
and
10
b
, which may be closed by jumper line
9
, are provided between the anode of diode
2
of diodes
2
,
3
,
4
,
5
and a, for example, 24V DC voltage terminal Vp. Also, contacts
12
a
and
12
b
, which may be closed by jumper line
11
, are provided between the cathode of diode
5
of diodes
2
,
3
,
4
,
5
and earth.
In the above composition, in the case of allowing sink input to be inputted at input terminal
1
, contacts
10
a
and
10
b
are closed by soldering jumper line
9
between them, and contacts SA for sink input are connected between input terminal
1
and common earth terminal
13
. On the other hand, in the case of allowing source input to be inputted at terminal
1
, contacts
12
a
and
12
b
are closed by soldering jumper line
11
between them, and contacts SB for source input are connected between a, for example, 24V DC input terminal Vi and input terminal
1
. By this means the above input circuit has a shared use composition for the two input methods.
However, with the above prior art composition, four diodes 2~5 and photocoupler
7
must be added for one input terminal
1
. This has the disadvantage of increasing production costs. In particular, many control devices are normally provided with about 10~100 input terminals. In such cases there was a risk that as many circuit compositions made up of diodes 2~5 and photocouplers
7
as there were input terminals would have to be provided, and the production costs would increase considerably.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide an interface circuit that, while having a composition able to cope with either sink input or source input, may reduce production costs.
To achieve the above object, in a circuit provided with an input terminal that deals with contact inputs and input signals such as logic, the interface circuit of the present invention provides
a means of switching that switches between a state in which a pull-up resistor is connected to the above-mentioned input terminal and a state in which a pull-down resistor is connected;
a means of discrimination that discriminates whether there is sink input or source input by discriminating the switch connection state of this means of switching; and a means of signal switching that switches between a signal output state that outputs an inverted signal of the above-mentioned input signal and a signal output state that outputs the said input signal as it stands, based on the discrimination result of this means of discrimination.
In the above composition, in the case of allowing sink input at the input terminal, the connection state in which the pull-up resistor is connected to the input terminal is produced by the means of switching. On the other hand, in the case of allowing source input at the input terminal, the connection state in which the pull-down resistor is connected to the input terminal is produced by the means of switching. Also, in the case of this composition, discrimination whether it is sink input or source input is performed by the above means of discrimination by discriminating the switch connection state of the above switching means. At the same time, the signal output state is switched by the means of signal switching between a signal output state that outputs an inverted signal of the input signal and a signal output state that outputs the input signal as it stands, based on the above discrimination result.
By this means, this becomes a composition that may deal with either sink input or source input. Moreover, the means of switching may be achieved by a low-cost composition such as a changeover switch. Also, the means of discrimination may be achieved by a low-cost composition such as a circuit that detects whether the voltage level of the terminal is high level or low level. Furthermore, the means of signal switching, too, may be achieved by such as a simple hardware circuit made up of a logic circuit and a changeover switch, or a microcomputer control function (software). Thus, overall production costs may be reduced.
Also, in the case of the above composition, a voltage detection circuit is provided that detects the voltage of the levels corresponding to the switch connection states of the above-mentioned means of switching. It is desirable that the above-mentioned means of discrimination should be so composed that it discriminates the switch connection state of the switching circuit, based on the voltage detected by the above-mentioned voltage detection circuit. Moreover, the means of switching may be composed by a manually-operated switch. Furthermore, it is desirable that the means of switching should be composed from a terminal block having a plural of pin terminals and connectors fitted on the pin terminals that short between specified pin terminals. Also, the above-mentioned means of switching may be composed from a plural of lands provided on a printed circuit board and jumper lines that are soldered to these lands and short between specified lands.
On the other hand, an even more desirable composition is to compose the above-mentioned means of switching from switching elements made up of relays or transistors and a means of switching control that exercises switching control of the above-mentioned switching elements based on external commands. Also, a desirable composition is one composed to provide a means of output switching that switches between an output method that outputs output signals by sink output and an output method that outputs signals by source output, based on the discrimination result of the above-mentioned means of discrimination.
Moreover, the device may be composed to provide a means of storage that stores the discrimination result discriminated by the above-mentioned means of discrimination at the previous time of operation, and a means of comparison that compares the discrimination result stored by this means of storage and the discrimination result discriminated by the above-mentioned means of discrimination at the current time of operation. In the case of this composition, an even more desirable composition is to provide a means of information that informs of the difference when the discrimination result by the means of discrimination at the previous time of operation and the discrimination result at the current time of operation are judged to differ.
Also, in the case of the above composition, it is also a good composition to prov
Endo Tamotsu
Goushi Youichi
Kabushiki Kaisha Toshiba
Kim Jung Ho
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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