Magnetic bubble memory having by-pass paths for defective loops

Claim 2

A magnetic memory apparatus comprising: a magnetic medium capable of holding bubble domains; magnetic means for permitting the domains to stably stay in the magnetic medium; magnetic means for propagating the domains; a plurality of memory loops; a transfer loop comprising; a first and a plurality of second domain propagation paths capable of circulating domains therein, each of said second paths beginning and ending in said first path and constituting a bypass of the part of said first path between said beginning and ending; means for selectively transferring the domains between the first domain propagating path and the plurality of memory loops to write and read data into or from the memory loops; means for detecting a defect in any memory loops which prevents the domains from propagating; means for operating any of said second domain propagating paths in order to cause the domains to pass therethrough and to avoid the part of said first domain propagating path which leads to the detected defective memory loop.

Claim 3

A magnetic memory apparatus of claim 1 in which there is provided a means for arbitrarily selecting one of said second domain propagation paths so that during the time interval for the domains to be transferred from a position in the transfer loop which leads to the memory loop located immediately before the defective memory loop to a position in the transfer loop which leads to the defective memory loop, the domains can reach the memory loop located immediately after the defective memory loop from the memory loop located immediately before the defective memory loop.

Claim 4

A magnetic memory apparatus of claim 2 in which the transfer loop has auxiliary paths connected thereto for keeping the effective length of the transfer loop constant and means for selectively operating said auxiliary paths depending on the number of defective memory loops to keep the effective length of the transfer loop constant.

Claim 5

A bubble domain memory of the type which is capable of storing bubble domains therein, said memory comprising, a. a plurality of memory loops for storing domains therein, each said memory loop having an entrance and being adapted to selectively receive domains which are at a position outside said memory loop but adjacent to said entrance and to selectively provide domains from said loop to said position outside said entrance, b. a transfer loop for circulating domains therein, said transfer loop comprising, i) a plurality of domain holding positions equal to, outside of, and adjacent to said respective entrances of said plurality of memory loops, ii. a plurality of normal domain paths, each one provided between a different pair of said domain holding positions, whereby the totality of said normal paths used provide a series path for carrying a domain successively to the domain holding positions adjacent to the entrances of each said memory loop, iii. a plurality of alternate paths, each positioned to bypass the domain holding position adjacent the entrance of a respective one of said memory loops, and iv. bypass control means, one associated with each said alternate path, for selectively causing a domain circulating in said transfer loop to travel along the corresponding alternate path thereby bypassing part of the normal path which normally carries the domain to the domain holding position adjacent the entrance of an associated memory loop.

Claim 6

A bubble domain memory of the type which is capable of storing bubble domains therein, said memory comprising, a. a plurality of memory loops for storing domains therein, each said memory loop having an entrance and being adapted to selectively receive domains which are at a position outside said memory loop but adjacent to said entrance and to selectively provide domains from said loop to said position outside said entrance, b. a transfer loop for circulating domains therein, said transfer loop comprising, i) a plurality of domain holding positions equal to, outside of, and adjacent to said respective entrances of said plurality of memory loops, ii. a plurality of normal domain paths, each one provided between a different pair of said domain holding positions, whereby the totality of said normal paths used provide a series path for carrying a domain successively to the domain holding positions adjacent to the entrances of each said memory loop, iii. a plurality of alternate paths, each positioned to bypass the domain holding position adjacent the entrance of a respective one of said memory loops, and iv. bypass control means, one associated with each said alternate path, for selectively causing a domain circulating in said transfer loop to travel along the corresponding alternate path thereby bypassing part of the normal path which normally carries the domain to the domain holding position adjacent the entrance of an associated memory loop.

Claim 7

A bubble domain memory as claimed in claim 4 wherein said transfer loop further has a number of auxiliary paths connected thereto for keeping the effective length of the transfer loop constant and auxiliary path blocking means associated with each of said auxiliary paths for selectively causing a circulating domain to bypass said auxiliary paths.

Claim 8

A bubble domain memory as clained in claim 4 wherein the effective path lengths of said alternate and normal paths are such that the effective path length between first and second domain holding positions via a said normal path is equal to the effective path length between said first and a third domain holding position via a said alternate path, where said first, second and third domain holding positions are positioned successively in said transfer loop in the direction of normal domain circulation.

Claim 9

A bubble domain memory as claimed in claim 6 wherein the effective path lengths of said normal path and said auxiliary path are substantially identical.

Claim 10

A bubble domain memory as claimed in claim 7 further comprising automatic means for activating the said bypass control means associated with each said memory loop that is defective and for activating all said auxiliary path blocking means except for a number equal to the number of activated bypass control means, whereby the decrease in path length of the transfer loop caused by the effective removal of certain normal paths is compensated by the effective addition of the non-blocked auxiliary paths.

Claim 11

A bubble domain memory as claimed in claim 4 wherein said normal and said alternate paths comprise thin film patterns of soft magnetic film positioned to direct the movement of a domain under the influence of a rotating magnetic field in the plane of said thin film patterns, and wherein said bypass control means comprises, for each said alternate path respectively, a thin film of soft magnetic material shaped in a pattern to hold a domain irrespective of the direction of said rotating magnetic field and position adjacent said alternate path and a said normal path, whereby a domain traveling in said normal path near said bypass control means will be diverted to said alternate path by the repelling force of a domain held at said bypass control means.

Claim 12

A bubble domain memory as claimed in claim 5 wherein said normal and said alternate paths comprise thin film patterns of soft magnetic film positioned to direct the movement of a domain under the influence of a rotating magnetic field in the plane of said thin film patterns, and wherein said bypass control means comprises, for each said alternate path respectively, a thin film soft magnetic material shaped in a pattern to hold a domain irrespective of the direction of said rotating magnetic field and positioned adjacent said alternate path and a said normal path, whereby a domain traveling in said normal path near said bypass control means will be diverted to said alternate path by the repelling force of a domain held at said bypass control means.

Claim 13

A bubble domain memory as claimed in claim 10 wherein said auxiliary path blocking means are substantially identical to said bypass control means.