# US 5,710,687 A · Lifter device for magnetic disk cartridge having a curved spring structure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,687 A - Document ID: US5710687A - Status: Granted - Kind: A - Application number: 08/574,034 - Filed: 1995-12-18 - Granted: 1998-01-20 - Earliest claimed: 1995-12-18 - Assignees: Sony Corporation; Sony Electronics Inc. - Inventors: Walter Duane Drebenstedt - Web page: https://patentgrep.com/patent/US5710687A ## CPC - G11B 23/0332: {for single discs, e.g. envelopes} - 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) ## Abstract A lifter device for a magnetic recording diskette which has a resilient, flexible, relatively rigid plastic sheeting, such as polyethylene terephthalate (PET). The lifter device curves upward from an inner surface of the casing to which it is affixed toward a pad which contacts the recording material within the diskette. The lifter maintains a desired amount of pressure against the pad over an extended range of operating conditions. ## Claims ### Claim 1 A disk apparatus comprising: a casing; a planar, circular shaped recording material rotatably disposed within said casing; a pair of pad members disposed on opposing surfaces of said recording material; and a spring structure comprising a resilient, flexible, relatively rigid plastic sheeting disposed within said casing, said spring structure having a lower portion affixed to an inner surface of said casing, said spring structure extending from said inner surface of said casing to contact one of said pair of pad members, thereby providing pressure against the one of said pair of pad members to which said spring structure portion contacts; wherein said spring structure consists essentially of polyethylene terephthalate; and wherein said spring structure has a convex curve shape on a side of said spring structure facing away from said pad members and wherein said spring structure has a radius of curvature of approximately 40 mm between an end portion and said lower portion prior to being compressed by the one of said pair of pad members to which said spring structure contacts. ### Claim 2 (depends on 1) A disk apparatus according to claim 1, wherein said convex curve shape extends over a length of said spring structure, and said spring structure exerts a substantially uniform pressure across a portion of the one of said pair of pad members to which said spring structure contacts. ### Claim 3 (depends on 1) A disk apparatus according to claim 1, wherein said spring structure has an end portion which is disposed approximately 7 mm apart from said inner surface of said casing prior to being compressed by the one of said pair of pad members to which said spring structure contacts. ### Claim 4 A lifter device for maintaining a predetermined amount of pressure between a pad and a recording medium disposed in a magnetic recording cartridge, said lifter device comprising: a curved leaf spring structure extending from a lower portion that is affixed to an inner surface of said casing toward said pad, said spring structure providing pressure against said pad; wherein said lifter device is formed of a resilient, flexible, relatively rigid plastic sheeting consisting essentially of polyethylene terephthalate; and wherein said spring structure has a convex curve shape on a side of said spring structure facing away from said pad, and wherein said spring structure has a radius of curvature of approximately 40 mm between an end portion and said lower portion prior to being compressed by said pad. ### Claim 5 (depends on 4) A lifter device as set forth in claim 4, wherein said convex curve shape extends over a length of said spring structure, and said spring structure exerts a substantially uniform pressure across a portion of the pad. ### Claim 6 (depends on 4) A lifter device as set forth in claim 4, wherein said lifter device has an end portion which is disposed approximately 7 mm apart from said inner surface of said casing prior to being compressed by said pad. ### Claim 7 A lifter device for maintaining a predetermined amount of pressure between a pad and a recording medium disposed in a magnetic recording cartridge, said lifter device comprising: a curved leaf spring structure having a first portion affixed to an inner surface of a casing of said cartridge and a second portion for contacting and providing a spring pressure against said pad, said spring structure having a convex curve shape prior to being compressed by said pad, said convex curve shape extending from said first portion to said second portion on a side of said spring structure facing said inner surface of said casing, wherein said spring structure has a radius of curvature of approximately 40 mm between said first and second end portions prior to being compressed by said pad. ### Claim 8 (depends on 7) A lifter device as set forth in claim 7, wherein said lifter device is formed of a resilient, flexible, relatively rigid plastic sheeting consisting essentially of polyethylene terephthalate. ### Claim 9 (depends on 7) A lifter device as set forth in claim 7, wherein said lifter device exerts a substantially uniform pressure across a portion of said pad. ### Claim 10 (depends on 7) A lifter device as set forth in claim 7, wherein said second portion of said spring structure is disposed approximately 7 mm apart from said inner surface of said casing prior to being compressed by said pad. ### Claim 11 (depends on 7) A lifter device as set forth in claim 7, wherein said convex curve shape is on a side of said spring structure facing away from said pad. ### Claim 12 A disk apparatus comprising: a casing having an outer and an inner surface; a planar, circular shaped recording material rotatably disposed within said casing; a pair of pad members disposed on opposing surfaces of said recording material; and a spring structure comprising a resilient, flexible, relatively rigid sheeting disposed within said casing, said spring structure having a first portion affixed to an inner surface of said casing and a second portion for contacting and providing a spring pressure against one of said pad members; wherein said spring structure has a convex curve shape prior to being compressed by said one of said pad members, said convex curve shape extending from said first portion to said second portion on a side of said spring structure facing said inner surface of said casing, and wherein said convex curve shape has a radius of curvature of approximately 40 mm prior to being compressed by said one of said pad members. ### Claim 13 (depends on 12) A disk apparatus according to claim 12, wherein skid spring structure exerts a substantially uniform pressure across a portion of said one of said pad members. ### Claim 14 (depends on 12) A disk apparatus according to claim 12, wherein said second portion of said spring structure is disposed approximately 7 mm apart from said inner surface of said casing prior to being compressed by said one of said pad members. ### Claim 15 (depends on 12) A disk apparatus according to claim 12, wherein said spring structure is formed of a plastic sheeting consisting essentially of polyethylene terephthalate. ### Claim 16 (depends on 12) A disk apparatus according to claim 12, wherein said convex curve shape is on a side of said spring structure facing away from said pad members.