Junction device with logic

Details Junction device with logic Junction device with logic

2001-06-15

2004-11-02

Toatley, Jr., Gregory J. (Department: 2836)

Electrical transmission or interconnection systems

Switching systems

Condition responsive

Reexamination Certificate

active

06812593

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates in general to interfaces and junction boxes and particular to a junction device that includes logic functions.
Robotics are being increasingly used in manufacturing situations to handle work pieces. Such robotic devices are known to pick up a work piece, transport the work piece to a work station, such a numerically controlled machining operation, and install the work piece upon the work station. The robotic devices often include an arm that can swing, extend and elevate to move the work piece. The work piece itself is held in a gripper attached to the end of the arm. Such grippers are usually designed to accommodate the specific work piece and can include a plurality of fingers that close upon and thereby grasp the work piece.
The grippers are usually equipped with a plurality of position sensors that determine the position of the gripper fingers relative to the work piece. Such position sensors may be simple limit switches that are mechanically closed or opened upon contact with the work piece or may be more sophisticated proximity sensors that generate an output current or voltage as the fingers approach the work piece. Position sensors also can be mounted upon the robotic arm itself. The proximity type position sensors typically have an output stage that provides the sensor output signal to the robotic device. Upon receiving sensor output signals that all of the fingers are in place upon the work piece, the robotic device will proceed to the next step of its cycle, such as, for example, transporting the work piece to the next work station. Thus, the robotic device must receive a number of sensor output signals.
Position sensors also find wide spread use on machine tools and other mechanical devices where automatic control of movement is required. Thus, automatic processing machines and manufacturing equipment frequently include position sensors in their control systems to provide input signals to their logic circuits.
As described above, the position sensor output signals may vary from simple contacts, such as limit switch or relay contacts to current sources generated by PNP output transistors to current sinks generated by NPN output transistors. Also, the input circuit of the associated robotic device may include either PNP, NPN or contact devices. In the past, a specific junction box that is compatible with both the specific sensor output signal and the specific robotic device input signal requirements has been provided. This has increased the complexity of the design of robotic devices. Accordingly, it would be desirable to provide a common junction device or box that would be compatible with the various sensor output signals. It also would be desirable to provide a logic function in the junction device or box to provide a single output signal to the robotic device once all the sensors are indicating a closed status. By moving the logic to the junction box or device, the complexity of the robotic device wiring would be significantly reduced.
Additionally, it is known to connect several proximity sensors in series. Thus, an input signal is provided when all of the sensors are in a “closed position”. With a prior art junction box, the signal generated by the series proximity sensors is passed directly to the junction box output However, it has been observed that when more than two proximity sensors are connected in series, the cumulative voltage drop across the sensors degrades the output signal excessively. Accordingly, it would be desirable to provide a junction box or device that is not affected by the series connection of sensors on an input to the box.
SUMMARY OF THE INVENTION
This invention relates to a junction device that includes logic functions.
The present invention is directed toward an improved junction box or device that receives output signals from a plurality of sensors and is operable to generate a single output upon receipt of output signals from all of the sensors. Additionally, the junction box or device includes the capability of providing an interface between a plurality of sensor output signal sources, such as a current source associated with a PNP solid state device, a current sink associated with a NPN solid state device, or a dry contact. Similarly, the output of the interface can be selected to be compatible with the input of the connected device. Thus, the junction box or device output also can be selected from one of a current source, a current sink or a dry contact output.
The present invention contemplates a plurality of rectifier bridge circuits that have input leads connected to the input signal terminals. The output leads of the rectifier bridge circuits are electrically connected to the inputs of a corresponding one of a plurality of optoisolator dual transistors. The optoisolator dual transistors are connected in series and thus function as an AND logic circuit. Connected between the optoisolator dual transistors are gate bias resistors for a pair of output power Field Effect Transistors (FET). The FET's are electrically connected to corresponding output terminals. A relay coil is connected to the drain of one of the output FET's.
Upon an input signal being present on all of the input terminals, all of the rectifier bridge circuits supply a current to their corresponding optoisolator dual transistor. The optoisolator dual transistors are responsive to the bridge circuit current to change from their non-conducting to their conducting state allowing a current to flow though the gate bias resistors for the output FET's. As a result, the gate voltages change and the FET's also change from their non-conducting to their conducting states which also pulls in the relay coil. Accordingly, current can flow through the output terminals connected to the FET's and any normally open relay contacts while current is blocked from flowing through any output terminals connected to normally closed relay contacts.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.


REFERENCES:
patent: 3711827 (1973-01-01), Houseman
patent: 4072936 (1978-02-01), Spirig
patent: 5460210 (1995-10-01), Koeninger
patent: 5495228 (1996-02-01), Futsuhara et al.
patent: 6271747 (2001-08-01), Fendt et al.

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