Logic circuit equivalent to a relay contact circuit

Abstract

A logic circuit comprises a serially connected circuit structure and a wired OR connected circuit structure of unit circuits, each of which is composed of logic elements and equivalent to a relay contact. The respective unit circuit is connected with associated equipment in a manner similar to that used in connecting relay contacts, on a base of a circuit diagram, whereby a logic circuit equivalent to the relay contact circuit is formed.

What is claimed is:  .[.1. A logic circuit comprising a plurality of unit circuits which are connected with each other in first and second connection types, each of said unit circuits comprising an AND element having at least two input terminals and an inverter element connected to one input of the AND element, each of said unit circuits being equivalent to one relay contact in operation, said first connection type being a connection type in which the output of the AND element of one unit circuit is connected to the output of the AND element of another unit circuit to form a wired OR connection whereby a circuit construction for carrying out an OR logical operation of unit circuits is formed, said second connection type being a connection type in which the output of the AND element of one unit circuit is connected to the input of the inverter element of another unit circuit, said other input terminal of said AND element of said unit circuits being connected to a signal source, whereby a circuit construction for carrying out an AND logical operation of unit circuits is formed, the all unit circuits being respectively connected with each other in the same sequence as the relay contacts..].  .[.2. A logic circuit according to claim 1 which further comprises circuit means for applying a driving signal to the other input of the AND element of the respective unit circuit, said driving signal being equivalent to a driving signal to energize a relay coil for driving the relay contact in operation..]. .[.3. A logic circuit according to claim 2 wherein said driving signal applying circuit means includes AND elements for operating responsive to a coincidence between incoming signals through two input terminals, and said driving signal applying circuit means being constructed to switch off each of said unit circuit means by removing the signal from one of said two input terminals at the time of interlocking..].  .[.4. A logic circuit according to claim 2 which further comprises time delay means including a separate capacitor connected to said driving signal applying circuit means to impart a time delay to the operation of the logic operation..].  .[.5. A logic circuit according to claim 1 which is constructed by using a plurality of circuit boards of one kind, each of the boards being provided with a plurality of said unit circuits and input and output terminals of said unit circuits, said first connection type being obtained by connecting the output terminals with each other on the same boards, and said second connection type being obtained by connecting the output terminals of one board with the input terminals of another board..]. .[.6. A logic circuit according to claim 5 wherein each of said plurality of circuit boards is provided with a DC stabilized power supply circuit for use in supplying the power only for unit circuits installed on the same circuit board..].  .[.7. A logic circuit according to claim 1 further comprising an interface circuit means connected to an external mechanical switch contact and to one input of the AND element of the unit circuit which is in the first stage among the unit circuits, said interface circuit supplying a signal of the switch contact to the AND element after eliminating chattering of the signal..].  .Iadd. 8. A logic circuit comprising a plurality of circuit board means of one kind, each of the boards having a plurality of unit circuits, each including input and output terminals, and means comprising a DC stabilized power supply circuit mounted on each of said circuit board means for supplying power to only those of said unit circuits which are installed on the same circuit board, each of said unit circuits comprising an AND element having at least two input terminals and an inverter element connected to one input of the AND element, each of said unit circuits being equivalent to one relay contact, said unit circuits being connected in a first connection type in which the output of the AND element of one unit circuit is connected to the output of the AND element of another unit circuit to form a wired OR connection whereby a logical OR circuit is formed, said first connection type being obtained by connecting the output terminals with each other on the same boards, said unit circuits being connected in a second connection type in which the output of the AND element of one unit circuit is connected to the input of the inverter element of another unit circuit, said other input terminal of said AND element of said unit circuits being connected to a signal source, whereby a logical AND circuit is formed, said second connection type being obtained by connecting the output terminals of one board with the input terminals of another board, all unit circuits being respectively connected with each other in the same sequence as relay contacts by an interconnection of a plurality of the circuit board means of one kind. .Iaddend. .Iadd. 9. A logic circuit according to claim 8 and negative logic means connected between said AND elements of the unit circuits. .Iaddend..Iadd. 10. A logic circuit according to claim 8 wherein each of the boards further comprises a terminal group including a plurality of terminals connected to the other terminals of said AND elements, and means for supplying two kinds of inputs to the terminal group, said terminals of the terminal group being selectively connected with each other whereby either one kind of input is supplied to the other terminal of the AND elements so that the unit circuits are selectively equivalent to normally open or normally closed relay contacts.