Null track for automatic stacker

Claim 2

A control circuit for positioning apparatus of the type in which a first member is movable along a predetermined path, and selectively to any one of a plurality of different positions of rest relative to a second member, comprising electrical conductors defining a plurality of spaced null points along said path at intervals corresponding to said positions of rest, means for selectively energizing said conductors simultaneously to place certain only of said null points selectively in stable and unstable modes, respectively, an actuatable sensor mounted on said first member for movement thereby into registry with successive ones of said null points during movement of said first member in one direction, and operative, when actuated, to stop and first member when moved into registry with a selected null point disposed in its stable mode, said energizing means including means operative to maintain only every other one of said certain null points in a stable mode during movement of said first member.

Claim 3

A control circuit as defined in claim 1, wherein said energizing means comprises first switch means operable to place simultaneously only alternate null points along said path in said stable and unstable modes, respectively, and second switch means operable to place simultaneously only the null points located between said alternate null points in said stable and unstable modes, respectively.

Claim 4

A control circuit as defined in claim 2, wherein said null points are defined by two pairs of conductors which extend along said path,

Claim 5

A control circuit as defined in claim 3, wherein said energizing means comprises an AC power supply, said first switch means comprises a first plurality of switches operable selectively to connect one of the conductors of said one pair to said power supply and the other conductor of said one pair to ground, thereby selectively to place either the odd or even numbered ones of said alternate null points in a stable mode, and said second switch means comprises a second plurality of switches operable selectively to connect one of the conductors of said other pair to said power supply and the other conductor of said other pair to ground, thereby selectively to place in a stable mode either the odd or even numbered ones of the null points located between said alternate points.

Claim 6

In a storage system having an automatic stacker that travels in an aisle adjacent a storage rack for registry with a selected bin in the rack, a device for halting the stacker, comprising a first pair of elecTrically-conductive wires crossed and recrossed at intervals intermediate their ends to form a first plurality of spaced crossover points that register with alternate bins in said rack, a second pair of wires being crossed and recrossed at intervals intermediate their ends to form a second plurality of spaced crossover points that alternate with those of said first plurality to register with intervening bins in said rack, means for selectively applying an AC voltage to said wires one pair at a time, thereby selectively to develop stable nulls at alternate crosspoints only in one pair of said wires, and a sensing head on the stacker moved in operative relation to said pairs of wires to stop said stacker when said head registers with a selected stable null.

Claim 7

In a storage system having an automatic stacker that travels in an aisle adjacent a storage rack for registry with a selected bin in the rack, a device for halting the stacker, comprising a first pair of elecTrically-conductive wires crossed and recrossed at intervals intermediate their ends to form a first plurality of spaced crossover points that register with alternate bins in said rack, a second pair of wires being crossed and recrossed at intervals intermediate their ends to form a second plurality of spaced crossover points that alternate with those of said first plurality to register with intervening bins in said rack, means for selectively applying an AC voltage to said wires one pair at a time, thereby selectively to develop stable nulls at alternate crosspoints only in one pair of said wires, and a sensing head on the stacker moved in operative relation to said pairs of wires to stop said stacker when said head registers with a selected stable null.

Claim 8

In a storage system as defined in claim 5, where said means comprises a first plurality of switches for selectively connecting each of said wires to an AC power supply, a second plurality of switches for selectively connecting each of said wires to ground, and control means operable selectively to close a first one each of said first and second pluralities of switches to apply AC voltage of one phase to one of said pairs of wires to develop stable nulls at its alternate crossover points, and to close a second one each of said first and second pluralities of switches to apply AC voltage of opposite phase to said one pair of wires to develop stable nulls at its intervening crossover points, between the alternate crossover points thereof. the two conductors of one pair thereof are connected to said first switch means and intersect each other at spaced intervals to form said alternate null points at the intersections thereof, and the two conductors of the other pair are connected to said second switch means and intersect each other at spaced intervals to form at the intersections null points alternating with the null points of said one set of conductors.

Claim 9

In a storage system comprising a storage rack having a plurality of bins arranged in horizontal rows and vertical columns, and a movable transporting member for depositing loads in and removing loads from the bins, electrically operative means for controlling the transporting member to determine at what bin it is to be stopped for deposit or removal of a load, comprising two pairs of electrically conductive wires, the wires of each pair crossing and recrossing one another at intervals, and the wires of one pair being disposed so that its points of crossing and recrossing alternate with those of the other pair in the direction of movement of the transporting member, means connected to said transporting member to move therewith for sensing the crossing points of the two pairs of wires, and means for selectively applying to each of said two pairs of wires one of two pulsating voltages having opposed phases.

Claim 10

In a storage system comprising a storage rack having a plurality of bins arranged in horizontal rows and vertical columns, and a movable transporting member for depositing loads in and removing loads from the bins, electrically operative means for controlling the transporting member to determine at what bin it is to be stopped for deposit or removal of a load, comprising two pairs of electrically conductive wires, the wires of each pair crossing and recrossing one another at intervals, and the wires of one pair being disposed so that its points of crossing and recrossing alternate with those of the other pair in the direction of movement of the transporting member, means connected to said transporting member to move therewith for sensing the crossing points of the two pairs of wires, and means for selectively applying to each of said two pairs of wires one of two pulsating voltages having opposed phases.