# US 5,703,735 A · Magnetic single point contact latch assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,735 A - Document ID: US5703735A - Status: Granted - Kind: A - Application number: 08/664,714 - Filed: 1996-06-17 - Granted: 1997-12-30 - Earliest claimed: 1993-05-06 - Assignees: Xolox Corporation - Inventors: William F. Bleeke - Web page: https://patentgrep.com/patent/US5703735A ## CPC - G11B 21/22: while the head is out of operative position - Y10T 24/32: having magnetic fastener - Y10T 292/11: Magnetic - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A single-point magnetic contact latch assembly for "parking" a read/write head of a memory storage device over a data-free landing zone during off-power conditions has one or more permanent magnets, a core having a curvilinear shape on one end and an annular flange formed on the opposing end, and a casing, having an open end and a partially closed end, covering the magnet(s). The core is disposed adjacent the magnet(s) and lies within the flux paths thereof. The casing covers the core and magnet(s) so that the curvilinear end of the core extends through the partially open end of the casing. The casing abuts an outer periphery surface of the flange with a press-fit so that the casing is outwardly radially deformed at the point of abutment securely anchoring the casing, and magnet(s) in position relative to the core. The single-point magnetic contact latch assembly is mounted to a crash stop of the memory storage device and engages a ferromagnetic portion of an actuator assembly used to position the read/write head along the storage device during off-power conditions, the latch assembly locating the read/write head over the landing zone to prevent damage to the memory storage device and the read/write head caused by physical contact between the two. An alternative embodiment of the magnetic latch assembly has a substantially spherically shaped core that also provides a single-point magnetic contact between the core and the actuation assembly. ## Claims ### Claim 1 A magnetic means for magnetically engaging a ferromagnetic strike plate of an actuator at a single point of magnetic contact to position a head assembly of a disk drive over a data storage device when power is off to said data storage device, said magnetic means comprising a ferromagnetic core with a contact end and an opposite end spaced along an axis thereof, and a permanent magnet with first and second poles spaced along an axis thereof, said axes being coincident with the majority of flux from the magnet being channeled through the ferromagnetic core to establish the single point of magnetic contact between the ferromagnetic core and the strike plate. ### Claim 2 A magnetic means for magnetically engaging a ferromagnetic strike plate of an actuator at a single point of magnetic contact to position a head assembly of a disk drive over a data storage device when power is off to said data storage device, said magnetic means comprising a ferromagnetic core with a contact end and an opposite end spaced along an axis thereof, and a permanent magnet with first and second poles spaced along an axis thereof, said axes being substantially parallel with the majority of flux from the magnet being channeled through the ferromagnetic core to establish the single point of magnetic contact between the ferromagnetic core and the strike plate. ### Claim 3 A magnetic means for magnetically engaging a ferromagnetic strike plate of an actuator at a single point of magnetic contact to position a head assembly of a disk drive over a data storage device when power is off to said data storage device, said magnetic means including a permanent magnetic and a ferromagnetic core with a first end of the core being adjacent a first magnetic pole of the magnet and a second end of the core being adjacent a second pole of the magnetic. ### Claim 4 A magnetic latch assembly for securing a read/write head of a disk drive during off power conditions, comprising: a magnet; a core positioned within flux paths of the magnet; a flange having first and second faces, the core projecting away from the first face of the flange; a casing in which the magnet and core are positioned to lie so that the magnet is covered to prevent portions of the magnet from falling off; and a pin projecting away from the second face of the flange and attaching the magnetic latch assembly to the disk drive. ### Claim 5 (depends on 4) The magnetic latch assembly of claim 4, wherein the core is generally cylindrically-shaped and the end of the core has a substantially continuous and uniform radius of curvature. ### Claim 6 (depends on 4) The magnetic latch assembly of claim 4, wherein an end of the casing is configured to define an opening and an end of the core extends through the opening beyond the end of the casing. ### Claim 7 (depends on 4) The magnetic latch assembly of claim 4, wherein the flange is annular. ### Claim 8 (depends on 7) The magnetic latch assembly of claim 7, wherein the casing is a hollow cylindrically-shaped shell having an axial length greater than an axial length of the magnet. ### Claim 9 (depends on 4) The magnetic latch assembly of claim 4, wherein an inner periphery of the casing engages an outer periphery of the flange to secure the casing to the flange with a press-fit, thereby securing the magnet within the casing. ### Claim 10 (depends on 4) The magnetic latch assembly of claim 4, wherein the magnet is cylindrically-shaped and configured to include a bore in which a portion of the core is positioned to lie so that an end of the core is outside of the bore. ### Claim 11 (depends on 10) The magnetic latch assembly of claim 10, wherein an end of the casing is configured to define an opening and the end of the core extends through the opening beyond the end of the casing. ### Claim 12 A magnetic latch assembly for securing a read/write head of a disk drive during off power conditions, comprising: a magnet; a core having an end, the core being positioned within flux paths of the magnet so that the end becomes a single point of magnetic contact for securing by itself the read/write head during off power conditions, the end being curved at the point of magnetic contact; and a casing having first and second ends, the first end having a first opening and the second end having a second opening, the first opening being smaller than the second opening, and the magnet and core being positioned within the casing so that the curved end of the core extends through the first opening beyond the first end of the casing. ### Claim 13 (depends on 12) The magnetic latch assembly of claim 12, further comprising a flange integrally formed on the core and positioned to lie within the casing so that portions of the magnet are prevented from falling off, and wherein the casing is secured to the annular flange with a press-fit. ### Claim 14 (depends on 13) The magnetic latch assembly of claim 13, (wherein the flange is annularly-shaped and has an outer periphery that is defined by a radius of substantially constant length that extends from a longitudinal axis of the core, and further wherein the press-fit results in a deformation of the casing that is adjacent the outer periphery of the flange in a direction away from the longitudinal axis of the core. ### Claim 15 (depends on 12) The magnetic latch assembly of claim 12, wherein the magnet is a one-piece structure. ### Claim 16 (depends on 12) The magnetic latch assembly of claim 12, wherein the curved end of the core extends radially from a longitudinal axis of the core. ### Claim 17 (depends on 16) The magnetic latch assembly of claim 16, wherein the curved end has a substantially continuous and uniform curvature. ### Claim 18 A magnetic latch assembly for securing a read/write head of a disk drive during off power conditions, comprising: a magnet; a core positioned within flux paths of the magnet, the core having an end that magnetically contacts a strike plate of the disk drive at a single point of magnetic contact to secure the read/write head and a longitudinal axis along which the end lies; and a pin positioned along the longitudinal axis of the core and attaching the magnetic latch assembly to the disk drive. ### Claim 19 (depends on 18) The magnetic latch assembly of claim 18, further comprising a casing having first and second ends, the first end having a first opening and the second end having a second opening, the magnet and core being positioned within the core so that the end of the core extends through the first opening of the casing. ### Claim 20 (depends on 18) The magnetic latch assembly of claim 18, wherein the magnet includes a plurality of magnetic pieces. ### Claim 21 (depends on 18) The magnetic latch assembly of claim 18, wherein the end of the core is defined by a radius extending from a point on the longitudinal axis to the end of the core. ### Claim 22 (depends on 21) The magnetic latch assembly of claim 21, wherein the radius has a constant length. ### Claim 23 (depends on 18) The magnetic latch assembly of claim 18, wherein the end of the core is curved. ### Claim 24 (depends on 18) The magnetic latch assembly of claim 18, wherein the core has a generally cylindrical shape.