EP0355692A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Rotary actuator for positioning magnetic heads in a disk drive
Assignee: Fujitsu Ltd
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Filing: 1989-08-16
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Granted: —
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Expires: 2009-08-16
Abstract
Abstract A rotary actuator for positioning magnetic heads in a disk drive, comprising a stator assembly and a rotor assembly. An arm assembly (9, 10) having magnetic heads (11) is fixed to the rotor assembly (4, 5, 9), which rotates back and forth within a limited angle range around a fixed axis (5) of the rotary actuator due to the forces between plural magnets (6, 7, 8) and a driving current which flows through flat coils (2, 3). Two flat coils (2, 3) are arranged on a arcuate inner surface (1s) of the stator such that two adjacent vertical parallel portions (2a, 3a) thereof closely contact with each other. The two flat coils (2, 3) have an electrical connection with a drive source such that the currents through the two adjacently parallel portions (2a, 3a) flow in the same direction. Three permanent magnets (6, 7, 8) are disposed on the rotor surface, the central magnet (7) having a greater lateral width than that of other two side magnets (6, 8), and a polarity of the central magnet (7) is opposite to that of other magnets (6, 8). In another embodiment, each of flat coils (2, 3) comprises an inner coil (2B, 3B) and an outer coil (2A, 3A) resulting in enhancing the torque of the rotary actuator. Several modifications of coil and permanent magnet arrangement, and other related improvements in the structure thereof are also disclosed.
Inventors
- 👤 Keiji Aruga
- 👤 Norihiko Suzuki
- 👤 Tomoyoshi Yamada
- 👤 Hiroshi Maeda
- 👤 Takahiro Imamura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 15:41
CPC Classifications
G; G11; G11B; G11B21/00; G11B21/02; G11B5/00; G11B5/48; G11B5/54; G11B5/55; G11B5/5521; H; H01; H01F; H01F7/00; H01F7/06; H01F7/08; H01F7/14; H01F7/145
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
240 words
A rotary actuator comprising: a stator including a yoke (1) having an arcuate inner surface (1s) extending in a longitudinal direction, a rotor (4) supported rotatably within a limited angle ϑ range around a fixed axis (5), the axis (5) being arranged in a region defined by said arcuate inner surface (1s) and parallel to said longitudinal direction, three permanent magnets (6, 7, 8) arranged on an outer surface of said rotor (4), the center magnet (7) having a lateral width larger than that of other two magnets (6, 8) and having substantially an equal distance from each of the other two magnets (6, 8) and a polarity of the central magnet (7) being opposite to that of other two magnets (6, 8), an arm (9), one end thereof being fixed to said rotor (4) and the other end projecting in an opposite direction toward said yoke (1), and two flat coils (2, 3), each coil (2, 3) being arranged on the inner surface (1s) of said yoke (1) and formed of two substantially parallel portions (2a, 2c, 3a, 3c) and two turning portions (2b, 2d, 3b, 3d), and adjacently arranged two parallel portions (2a, 3a) of said two flat coils (2, 3) closely contacting with each other facing the center magnet (7) and having electrical connection to a powder source such that electric currents flowing through said two adjacently arranged parallel portions (2a, 3a) are in the same direction.
Claim 2
Dependent Claim
240 words
A rotary actuator comprising: a stator including a yoke (1) having an arcuate inner surface (1s) extending in a longitudinal direction, a rotor (4) supported rotatably within a limited angle ϑ range around a fixed axis (5), the axis (5) being arranged in a region defined by said arcuate inner surface (1s) and parallel to said longitudinal direction, three permanent magnets (6, 7, 8) arranged on an outer surface of said rotor (4), the center magnet (7) having a lateral width larger than that of other two magnets (6, 8) and having substantially an equal distance from each of the other two magnets (6, 8) and a polarity of the central magnet (7) being opposite to that of other two magnets (6, 8), an arm (9), one end thereof being fixed to said rotor (4) and the other end projecting in an opposite direction toward said yoke (1), and two flat coils (2, 3), each coil (2, 3) being arranged on the inner surface (1s) of said yoke (1) and formed of two substantially parallel portions (2a, 2c, 3a, 3c) and two turning portions (2b, 2d, 3b, 3d), and adjacently arranged two parallel portions (2a, 3a) of said two flat coils (2, 3) closely contacting with each other facing the center magnet (7) and having electrical connection to a powder source such that electric currents flowing through said two adjacently arranged parallel portions (2a, 3a) are in the same direction.
Claim 3
Dependent Claim
338 words
A rotary actuator for positioning a read/write magnetic head (11) on the target track on a disk assembly (DA), the disk assembly (DA) having spindle means (36) for rotating the disks (37) around a spindle axis, the spindle means (36) being supported by upper and lower portions of a disk enclosure (38), the rotary actuator (OM) being positioned at one corner of the disk enclosure (38), having arm means (32, 9) for moving the magnetic head (31, 11) back and forth in a radial direction of the disk (37) with the rotation of the rotary actuator (OM), said rotary actuator comprising: a stator including a yoke (1) having an arcuate inner surface (1s) extending in a longitudinal direction, a rotor (4) supported rotatably within a limited angle ϑ range around a fixed axis (5), the fixed axis (5) being arranged in a region defined by said arcuate inner surface (1s) and parallel to said longitudinal direction, three permanent magnets (6, 7, 8) arranged on an outer surface of said rotor (4), the center magnet (7) having a lateral width larger than that of other two magnets (6, 8) and having substantially an equal distance from each of the other two magnets (6, 8) and a polarity of the central magnet (7) being opposite to that of other two magnets (6, 8), an arm (9), one end thereof being fixed to said rotor (4) and the other end projecting in an opposite direction toward said yoke (1), and two flat coils (2, 3), each coil (2, 3) being arranged on the inner surface (1s) of said yoke (1) and formed of two substantially parallel portions (2a, 2c, 3a, 3c) and two turning portions (2b, 2d, 3b, 3d), and adjacently arranged two parallel portions (2a, 3a) of said two flat coils (2, 3) closely contacting with each other facing the center magnet (7) and having electrical connection to a powder source such that electric currents flowing through said two adjacently arranged parallel portions (2a, 3a) are in the same direction.
Claim 4
Dependent Claim
338 words
A rotary actuator for positioning a read/write magnetic head (11) on the target track on a disk assembly (DA), the disk assembly (DA) having spindle means (36) for rotating the disks (37) around a spindle axis, the spindle means (36) being supported by upper and lower portions of a disk enclosure (38), the rotary actuator (OM) being positioned at one corner of the disk enclosure (38), having arm means (32, 9) for moving the magnetic head (31, 11) back and forth in a radial direction of the disk (37) with the rotation of the rotary actuator (OM), said rotary actuator comprising: a stator including a yoke (1) having an arcuate inner surface (1s) extending in a longitudinal direction, a rotor (4) supported rotatably within a limited angle ϑ range around a fixed axis (5), the fixed axis (5) being arranged in a region defined by said arcuate inner surface (1s) and parallel to said longitudinal direction, three permanent magnets (6, 7, 8) arranged on an outer surface of said rotor (4), the center magnet (7) having a lateral width larger than that of other two magnets (6, 8) and having substantially an equal distance from each of the other two magnets (6, 8) and a polarity of the central magnet (7) being opposite to that of other two magnets (6, 8), an arm (9), one end thereof being fixed to said rotor (4) and the other end projecting in an opposite direction toward said yoke (1), and two flat coils (2, 3), each coil (2, 3) being arranged on the inner surface (1s) of said yoke (1) and formed of two substantially parallel portions (2a, 2c, 3a, 3c) and two turning portions (2b, 2d, 3b, 3d), and adjacently arranged two parallel portions (2a, 3a) of said two flat coils (2, 3) closely contacting with each other facing the center magnet (7) and having electrical connection to a powder source such that electric currents flowing through said two adjacently arranged parallel portions (2a, 3a) are in the same direction.
Claim 5
Dependent Claim
66 words
A rotary actuator as recited in claim 1 or 2, wherein a total lateral width of said two adjacently arranged parallel portions (2a, 3a) is larger than a lateral width of said center magnet (7), and each lateral width of the remaining parallel portions (2c, 3c) of said two flat coils (2, 3) is larger than each lateral width of the remaining two magnets (6, 8).
Claim 6
Dependent Claim
41 words
A rotary actuator as recited in anyone of claims 1 to 3, wherein a longitudinal length of parallel portions (2a, 2c, 3a, 3c) of said two flat coils (2, 3) is larger than that of three permanent magnets (6, 7, 8).
Claim 7
Dependent Claim
26 words
A rotary actuator as recited in claim 3,wherein said lateral width of the center magnet (7) is substantially twice that of other two magnets (6, 8).
Claim 8
Dependent Claim
96 words
A rotary actuator as recited in anyone of claims 1 to 5, wherein each of said two flat coils (2, 3) comprises an inner coil (2B, 3B) and an outer coil (2A, 3A), each of the inner and outer coils having two parallel portions (2Aa, 2Ac, 2Ba, 2Bc, 3Aa, 3Ac, 3Ba, 3Bc) and two turning portions (2Ab, 2Ad, 2Bb, 2Bd, 3Ab, 3Ad, 3Bb, 3Bd), the inner coil being arranged inside the outer coil, and having electrical connection to the power source such that currents flowing through said inner and outer coils are in the same direction.
Claim 9
Dependent Claim
86 words
A rotary actuator as recited in claim 6, wherein said arrangement of the inner coil (2B, 3B) includes that one parallel portion (2Ba, 3Ba) of each said inner coils (2B, 3B) on the center side closely contacts with the respective parallel portion (2Aa, 3Aa) of the outer coil (2A, 3A) on the center side, and a gap remains between the other parallel portion (2Bc, 3Bc) of each said inner coil (2B, 3B) and the other respective parallel portion (2Ac, 3Ac) of the outer coil (2A, 3A).
Claim 10
Dependent Claim
38 words
A rotary actuator as recited in claim 6 or 7, wherein two turning portions (2Bb, 2Bd) of said each inner coil (2B) are bent outwardly and disposed on the turning portions (2Ab, 2Ad) of the outer coil (2A).
Claim 11
Dependent Claim
72 words
A rotary actuator as recited in claim 8, wherein a recess (15) is formed on the inner surface (1s) of said yoke (1), the recess being located at a corresponding position of said outwardly bent turning portion (2Bb, 2Bd, 3Bb, 3Bd) of said inner coil (2B, 3B), and having a sufficient size for receiving it when said flat coil (2, 3) is arranged on the inner surface (1s) of said yoke (1).
Claim 12
Dependent Claim
222 words
A rotary actuator comprising: a stator including a yoke (1) having an arcuate inner surface extending in a longitudinal direction, three permanent magnets (56, 57, 58) arranged on the inner surface of said yoke (1), the center magnet (57) having a lateral width larger than that of other two magnets (56, 58) and having substantially an equal distance from each of the other two magnets (56, 58) and a polarity of the central magnet (57) being opposite to that of other two magnets (56, 58), a rotor (4) supported rotatably within a limited angle ϑ range around a fixed axis, the axis being arranged in a region defined by said arcuate inner surface and parallel to said longitudinal direction, an arm (9), one end thereof being fixed to said rotor and the other end projecting in an opposite direction toward said yoke (1), and two flat coils (52, 53), each coil (52, 53) being arranged on an outer surface of said rotor (4) and formed of two substantially parallel portions and two turning portions, and adjacently arranged two parallel portions of said two flat coils (52, 53) closely contacting with each other facing the center magnet (57) and having electrical connection to a powder source such that electric currents flowing through said two adjacently arranged parallel portions are in the same direction.
Claim 13
Dependent Claim
222 words
A rotary actuator comprising: a stator including a yoke (1) having an arcuate inner surface extending in a longitudinal direction, three permanent magnets (56, 57, 58) arranged on the inner surface of said yoke (1), the center magnet (57) having a lateral width larger than that of other two magnets (56, 58) and having substantially an equal distance from each of the other two magnets (56, 58) and a polarity of the central magnet (57) being opposite to that of other two magnets (56, 58), a rotor (4) supported rotatably within a limited angle ϑ range around a fixed axis, the axis being arranged in a region defined by said arcuate inner surface and parallel to said longitudinal direction, an arm (9), one end thereof being fixed to said rotor and the other end projecting in an opposite direction toward said yoke (1), and two flat coils (52, 53), each coil (52, 53) being arranged on an outer surface of said rotor (4) and formed of two substantially parallel portions and two turning portions, and adjacently arranged two parallel portions of said two flat coils (52, 53) closely contacting with each other facing the center magnet (57) and having electrical connection to a powder source such that electric currents flowing through said two adjacently arranged parallel portions are in the same direction.
Claim 14
Dependent Claim
76 words
A rotary actuator as recited in claim 10, wherein each of said two flat coils (52, 53) comprises an inner coil (52B, 53B) and an outer coil (52A, 53A), each of the inner and outer coil having two parallel portions and two turning portions, the inner coil being arranged inside the outer coil, and having electrical connection to the power source such that current flowing through said inner and outer coils are in the same direction.
Claim 15
Dependent Claim
210 words
A rotary actuator comprising: a stator including a yoke (61) having an arcuate inner surface extending in a longitudinal direction, a rotor (62) supported rotatably within a limited angle range around a fixed axis (63), the axis (63) being arranged in a region defined by said arcuate inner surface and parallel to said longitudinal direction, two permanent magnets (65, 66) arranged on an outer surface of said rotor (62), a polarity of two magnets (65, 66) being opposite with each other, an arm, one end thereof being fixed to said rotor (62) and the other end projecting in an opposite direction toward said yoke (61), and a pair of flat coils (2A, 2B) arranged on the inner surface of said yoke (61) and comprising an inner coil (2B) and an outer coil (2A), each coil (2A, 2B) having two parallel portions (2Aa, 2Ac, 2Ba, 2Bc) and two turning portions, the inner coil (2B) being arranged inside the outer coil (2A), two turning portions of the inner coil (2B) being bent outwardly and disposed on the turning portions of the outer coil (2B), both coils (2A, 2B) having electrical connection to a power source such that currents flowing through said inner and outer coils (2A, 2B) are in the same direction.
Claim 16
Dependent Claim
210 words
A rotary actuator comprising: a stator including a yoke (61) having an arcuate inner surface extending in a longitudinal direction, a rotor (62) supported rotatably within a limited angle range around a fixed axis (63), the axis (63) being arranged in a region defined by said arcuate inner surface and parallel to said longitudinal direction, two permanent magnets (65, 66) arranged on an outer surface of said rotor (62), a polarity of two magnets (65, 66) being opposite with each other, an arm, one end thereof being fixed to said rotor (62) and the other end projecting in an opposite direction toward said yoke (61), and a pair of flat coils (2A, 2B) arranged on the inner surface of said yoke (61) and comprising an inner coil (2B) and an outer coil (2A), each coil (2A, 2B) having two parallel portions (2Aa, 2Ac, 2Ba, 2Bc) and two turning portions, the inner coil (2B) being arranged inside the outer coil (2A), two turning portions of the inner coil (2B) being bent outwardly and disposed on the turning portions of the outer coil (2B), both coils (2A, 2B) having electrical connection to a power source such that currents flowing through said inner and outer coils (2A, 2B) are in the same direction.
Claim 17
Dependent Claim
150 words
A rotary actuator comprising: a stator assembly including a stator yoke (104) having a arcuate inner surface extending in a longitudinal direction, and a plurality of coils (2, 3), an actuator assembly including an arm assembly (102) and a rotor assembly (103), said arm assembly (102) supported rotatably within a limited angle range around a fixed axis (5), the axis (5) being arranged in a region defined by said arcuate inner surface and parallel to the longitudinal direction, said rotor assembly (103) comprising a rotor yoke (4) and a plurality of permanent magnets (6, 7, 8) fixed on an outer surface of the rotor yoke (4) and facing said plurality of said coils (2, 3), and an elastic adhesive layer (100) formed between said rotor assembly (103) and arm assembly (102), whereby the elastic adhesive layer (100) has a function of a dynamic damper when the actuator assembly is excited.
Claim 18
Dependent Claim
150 words
A rotary actuator comprising: a stator assembly including a stator yoke (104) having a arcuate inner surface extending in a longitudinal direction, and a plurality of coils (2, 3), an actuator assembly including an arm assembly (102) and a rotor assembly (103), said arm assembly (102) supported rotatably within a limited angle range around a fixed axis (5), the axis (5) being arranged in a region defined by said arcuate inner surface and parallel to the longitudinal direction, said rotor assembly (103) comprising a rotor yoke (4) and a plurality of permanent magnets (6, 7, 8) fixed on an outer surface of the rotor yoke (4) and facing said plurality of said coils (2, 3), and an elastic adhesive layer (100) formed between said rotor assembly (103) and arm assembly (102), whereby the elastic adhesive layer (100) has a function of a dynamic damper when the actuator assembly is excited.
Claim 19
Dependent Claim
246 words
A rotary actuator for positioning a read/write magnetic head (11) on the target track on a disk assembly (DA), the disk assembly (DA) having spindle means (36) for rotating the disks (37) around a spindle axis, the spindle means (36) being supported by upper and lower portions of a disk enclosure (38), the rotary actuator (OM) being positioned at one corner of the disk enclosure (38), having arm means (102, 9) for moving the magnetic head (11) back and forth in a radial direction of the disk (37) with the rotation of the rotary actuator (OM), said rotary actuator comprising: a stator assembly including a stator yoke (104) having an arcuate inner surface extending in a longitudinal direction, and a plurality of coils (2, 3), an actuator assembly including an arm assembly (102) and a rotor assembly (103), said arm assembly (102) supported rotatably within a limited angle range around a fixed axis (5), the axis (5) being arranged in a region defined by said arcuate inner surface and parallel to the longitudinal direction, said rotor assembly (103) comprising a rotor yoke (4) and a plurality of permanent magnets (6, 7, 8) fixed on an outer surface of the rotor yoke (4) and facing said plurality of said coils (2, 3), and an elastic adhesive layer (100) formed between said rotor assembly (103) and arm assembly (102), whereby the elastic adhesive layer (100) has a function of a dynamic damper when the actuator assembly is excited.
Claim 20
Dependent Claim
246 words
A rotary actuator for positioning a read/write magnetic head (11) on the target track on a disk assembly (DA), the disk assembly (DA) having spindle means (36) for rotating the disks (37) around a spindle axis, the spindle means (36) being supported by upper and lower portions of a disk enclosure (38), the rotary actuator (OM) being positioned at one corner of the disk enclosure (38), having arm means (102, 9) for moving the magnetic head (11) back and forth in a radial direction of the disk (37) with the rotation of the rotary actuator (OM), said rotary actuator comprising: a stator assembly including a stator yoke (104) having an arcuate inner surface extending in a longitudinal direction, and a plurality of coils (2, 3), an actuator assembly including an arm assembly (102) and a rotor assembly (103), said arm assembly (102) supported rotatably within a limited angle range around a fixed axis (5), the axis (5) being arranged in a region defined by said arcuate inner surface and parallel to the longitudinal direction, said rotor assembly (103) comprising a rotor yoke (4) and a plurality of permanent magnets (6, 7, 8) fixed on an outer surface of the rotor yoke (4) and facing said plurality of said coils (2, 3), and an elastic adhesive layer (100) formed between said rotor assembly (103) and arm assembly (102), whereby the elastic adhesive layer (100) has a function of a dynamic damper when the actuator assembly is excited.
Claim 21
Dependent Claim
147 words
A rotary actuator comprising: a stator assembly including a stator yoke (104) having an arcuate inner surface extending in a longitudinal direction, and a plurality of permanent magnets (56, 57, 58), an actuator assembly including an arm assembly (102) and a rotor assembly (103), said arm assembly (102) supported rotatably within a limited angle range around a fixed axis, the axis being arranged in a region defined by said arcuate inner surface and parallel to the longitudinal direction, said rotor assembly (103) comprising a rotor yoke and a plurality of coils (2, 3) fixed on an outer surface of the rotor yoke and facing said plurality of permanent magnets (56, 57, 58), and an elastic adhesive layer (100) formed between said rotor assembly (103) and arm assembly (102), whereby the elastic adhesive layer (100) has a function of a dynamic damper when the actuator assembly is excited.
Claim 22
Dependent Claim
147 words
A rotary actuator comprising: a stator assembly including a stator yoke (104) having an arcuate inner surface extending in a longitudinal direction, and a plurality of permanent magnets (56, 57, 58), an actuator assembly including an arm assembly (102) and a rotor assembly (103), said arm assembly (102) supported rotatably within a limited angle range around a fixed axis, the axis being arranged in a region defined by said arcuate inner surface and parallel to the longitudinal direction, said rotor assembly (103) comprising a rotor yoke and a plurality of coils (2, 3) fixed on an outer surface of the rotor yoke and facing said plurality of permanent magnets (56, 57, 58), and an elastic adhesive layer (100) formed between said rotor assembly (103) and arm assembly (102), whereby the elastic adhesive layer (100) has a function of a dynamic damper when the actuator assembly is excited.
Claim 23
Dependent Claim
36 words
A rotary actuator as recited in claims 13, 14 or 15, wherein said rotor assembly (103) held by the elastic adhesive layer (100) has a natural vibration frequency close to that of said arm assembly (102).
Claim 24
Dependent Claim
65 words
A rotary actuator as recited in anyone of claims 1 to 16, wherein said fixed axis (5, 105) of the rotor provides means for fixing both end portions (5c, 5d) of the rotor to the said walls of the upper and lower portions of the disk enclosure (38), the side walls being formed for an opening to install the rotary actuator to the disk enclosure.
Claim 25
Dependent Claim
57 words
A rotory actuator as recited in claim 17, wherein said fixing means comprises a hole (1c, 1d) formed at both end portions of the axis, the direction of the hole being vertical to the direction of said axis (5, 105), whereby the rotary actuator is fixed to the disk enclosure using the hole and a bolt (12).
Claim 26
Dependent Claim
111 words
A rotary actuator as recited in anyone of claims 1 to 18, wherein said stator further comprises a stator housing (39), the stator housing (39) being fixed to the disk enclosure (38) at said one corner and forming a part of a completed disk enclosure, said yoke (1, 104) being fixed to an inner wall surface of the stator housing (39), and said two flat coils (2, 3) are fastened to the inner surface of the yoke (1, 104), whereby heat generated in the flat coils (2, 3) is removed from an outer surface of the stator housing (39) by thermal conduction through the yoke (1, 104) and stator housing (39).
Claim 27
Dependent Claim
129 words
A rotary actuator as recited in anyone of claims 1 to 19, wherein said other end of the arm has a first wall surface, the first wall surface having a first direction parallel to said longitudinal direction and a second direction vertical to the first direction and oblique to that of the disk rotation, and a connector (23, 25) is provided, the connector being assembled with a head assembly (10) at one end and having a second wall surface at the other end, the second wall surface mating with the first wall surface of the arm and being assembled therewith, and the center line (CL) of a combination of the head assembly (10) and connector (23, 25) is substantially in the same direction as that of the arm (9).
References Cited (Backward Citations)
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