US3827081A - Device for the displacement of magnetic read/write heads - Google Patents

Device for the displacement of magnetic read/write heads Download PDF

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Publication number
US3827081A
US3827081A US00264640A US26464072A US3827081A US 3827081 A US3827081 A US 3827081A US 00264640 A US00264640 A US 00264640A US 26464072 A US26464072 A US 26464072A US 3827081 A US3827081 A US 3827081A
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US
United States
Prior art keywords
carriage
core
dash
pot
magnetic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00264640A
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English (en)
Inventor
L Prieur
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bull SAS
Original Assignee
Societe Industrielle Honeywell Bull
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Societe Industrielle Honeywell Bull filed Critical Societe Industrielle Honeywell Bull
Application granted granted Critical
Publication of US3827081A publication Critical patent/US3827081A/en
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Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/54—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head into or out of its operative position or across tracks
    • G11B5/55—Track change, selection or acquisition by displacement of the head
    • G11B5/5521—Track change, selection or acquisition by displacement of the head across disk tracks
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B5/60—Fluid-dynamic spacing of heads from record-carriers
    • G11B5/6005—Specially adapted for spacing from a rotating disc using a fluid cushion

Definitions

  • the present invention deals with a clamping device for the displacement of magnetic heads, a device which is especially designed for disk memory units to guide such heads onto the desired recording track of the disks or to remove the head from the recording track.
  • the magnetic heads are carried by a sliding carriage driven by an electric motor of the type termed voicecoil, which includes a mobile electric coil positioned in a magnetic field and fed by a current of variable intensity and polarity.
  • voicecoil which includes a mobile electric coil positioned in a magnetic field and fed by a current of variable intensity and polarity.
  • this magnetic field is generated by a permanent magnet which is provided with a cylindric shell sheathing a cylindric magnetic core over which the coil is arranged coaxially.
  • voicecoil which includes a mobile electric coil positioned in a magnetic field and fed by a current of variable intensity and polarity.
  • this magnetic field is generated by a permanent magnet which is provided with a cylindric shell sheathing a cylindric magnetic core over which the coil is arranged coaxially.
  • Such a motor is known to subject the carriage which carries the magnetic heads to very sizable accelerations which may attain g.
  • the present invention removes this disadvantage of the prior art.
  • the damping device for the displacement of magnetic heads includes a sliding carriage carrying the magnetic heads which is driven by an electric motor consisting of a coil which is integral with said carriage and placed in a magnetic field of a permanent magnet that includes a cylindric magnetic core over which said coil is placed coaxially, and is distinguished in that it includes an air dash-pot whose one component is solidly attached to the carriage and the other to said core of the permanent magnet.
  • an electric motor consisting of a coil which is integral with said carriage and placed in a magnetic field of a permanent magnet that includes a cylindric magnetic core over which said coil is placed coaxially, and is distinguished in that it includes an air dash-pot whose one component is solidly attached to the carriage and the other to said core of the permanent magnet.
  • the two component parts of the dash-pots one dimension, parallel to the direction of the displacement of the carriage, is relatively short in relation to the course of the latter and no interacting of the one with the other occurs, except when the carriage happens to be in the vicinity of the core.
  • either component of the dash-pot is equipped with at least one cylindric protrusion in fixed connection with a base plate, cooperating with a cylindric protrusion of the other to form at least one couple comprising a cylinder and a piston.
  • the component parts may include several other cylindric protrusions integral with said base plates and coaxial with the former, these other protrusions of the one fitting into those of the other.
  • circulation baffle-plates are obtained for the air enclosed in the dash-pot.
  • the two parts of the dash-pot be arranged coaxially with the magnetic core and with the carriage. In this way it is possible to use this dashpot for centering purposes in the mounting of the carriage and the coil relative to the core.
  • the two component parts of the dash-pot are equipped with central tubular protrusions making it possible to pass the movable part of the pick-up therethrough and forming a piston-cylinder couple.
  • the dash-pot may best make use of the dash-pot for centering the pick-up so as to avoid the machining of this cylinder bore with the high degree of precision necessary.
  • the component part integral with the core in this case has in a cylindric protrusion whose interior diameter corresponds with that of the cylinder bore, this part resting with the flat surface of its base plate on the flat surface of the core end.
  • this part is centered in relation to the core by fitting it with a sleeve which it carries on the flat face in a cylinder bore of short length, coaxial with the cylinde'r bore of the pick-up and of a greater diameter than the latter.
  • the part of the dash-pot attached to the carriage includes at least one magnetic section which is attracted to the core by the magnetic field.
  • the magnetic field of the latter acts on the magnetic section by generating a retention force in this position. A force greater than this force must then be generated to remove the carriage from the magnet. The carriage, therefore, cannot accidentally move by itself in the direction of the magnetic support.
  • FIG. 1 is a schematic illustration of the device to which the invention is applied
  • FIGS. 2 and 3 are enlarged fragmentary longitudinal sectional views taken through two embodiments of the dash-pot, according to the invention. Identical reference numerals denote the same elements in these figures.
  • the damping device for the displacement of magnetic heads shown in FIG. 1, includes a carriage 1 capable of sliding on the rails 2 and 3 in the direction of the arrows F and F
  • the carriage I carries magnetic heads (not shown) and is driven by a motor 4 of the voice-coil type.
  • the motor 4 includes a cylindric coil 5 integral with the carriage l and a permanent magnet equipped with a cylindric shell 6 in the shape of a partially enclosed hollow cylinder in whose interior a cylindric magnetic core 7 is positioned.
  • the cylindric coil 5 is coaxial with the core 7, an air-gap 8 of the magnet being formed between the rim of the shell 6 and the free end of the core 7.
  • the movement of the coil 5, hence of the carriage I, is controlled by the current of variable amplitude and polarity passing through said coil.
  • the carriage 1 moves in the direction of the arrow F it approaches magnetic data storage (not shown) and in the direction of the arrow F it withdraws from it.
  • this dash-pot comprises two component parts 11 and 12 which interact and which are fixedly mounted on the core 7 and the carriage 1, respectively by any suitable means.
  • the part 11 includes a flat base plate 13 by which it is firmly attached to the flat surface of the end 14 of the core 7 and two tubular protrusions 15 and 16.
  • the part 12 comprises in the same manner a flat base plate 17 by which it is fixed to a flat surface 28 of the carriage 1 opposing the core 7, and two tubular protrusions 18 and 19.
  • the one dimension of the protrusions 15, 16, 18, and 19, parallel to the direction F and F is relatively short, so that in the rest position of the heads (extreme position of the carriage in the direction F the situation is avoided where the carriage 1 lies remote from the core 7, which would result in an excessive space requirement.
  • the parts 11 and 12 do not interact (position shown in FIG. 2).
  • the protrusions 16 and 18 act as cylinders for the protrusions 15 and 19, respectively which serve as pistons.
  • the air enclosed and compressed in the ringlike cavity, defined by the pair of cylinders and pistons prevents the carriage 1 from striking the motor 4, and brakesit gently. In the course of its compression the air escapes partly between the protrusions l5, l8, and partly between the protrusions 16, 19. Thereafter, the damping quality of the carriage 1 depends on relative play between these protrusions.
  • the tubular protrusions 16 and 19 permit the passing of the movable magnetic shaft 20 of a carriage velocity pick-up.
  • This pick-up of a known type, comprises a coil 21 which is located in the central longitudinal cylinder bore 22 of the core 7 which surrounds the shaft 20, attached to one of the ends of the carriage 1.
  • the coil 21 is insulated from the core 7 by a sheathing tube 23.
  • dash-pot 11-12 makes possible the centering of the coil 5 and the carriage 1 relative to the core 7.
  • the protrusion 16 of the part 11 has an inner diameter equal to that of the cylinder bore 22. In this fashion this part 11 may function,
  • the cylinder bore 22 has a widening or counterbore 24 into which a sleeve 25 is entered.
  • the sleeve 25 is integral with the surface of the base plate 13 in opposing relation to the flat surface of the core 7.
  • the part 12 is, for example, fabricated of a plastic material and is provided with a flange 26 of a magnetic material adapted to be attracted by the magnetic field 6, 7.
  • the parts 11 and 12 of the dash-pot may include other encased tubular protrusions, coaxial with the protrusions 15, 16, 18, and 19 to function as baffle plates for the air compressed between these parts. These other encased protrusions may slide in relation to each other by gentle friction so as to form pistoncylinder couples, or simply may slide with loose fitting engagement.
  • a damping device comprising a carriage for magnetic heads mounted for sliding movement, an electric motor drivingly connected to said carriage, said electric motor including a permanent magnet having a cylindric magnetic core and a coil carried by said carriage for movement therewith and arranged in telescopic coaxial relation with said core, and said damping device being an air dash-pot positioned axially between said core and said carriage, said dash-pot including two component parts one each fixedly secured to said core and said carriage.
  • a device characterized by the dimension of each of the two component parts of the dash-pot in the direction of the displacement of the carriage being relatively short in proportion to the movement of the carriage and said dash-pot component parts being free of interacting with each other except when the carriage is in the vicinity of said core.
  • a device characterized by at least one of the component parts of the dash-pot comprising at least one cylindric protrusion projecting from a base plate and interacting with a cylindric protrusion of the other component part to form at least one cylinder-piston couple.
  • a device characterized by the component parts of the dash-pot including each several other cylindric protrusions integral with respective base plates and coaxial with the first mentioned cylindric protrusions, at least one cooperating pair of said protrusions fitting with play.
  • a device characterized by the two component parts of the dash-pot being arranged coaxially with the magnetic core and the carriage.
  • a device including said carriage having a velocity pick-up positioned in a cylinder bore coaxial with said magnetic core, the two component parts of the dash-pot include base plates having tubular central protrusions projecting therefrom in co- 8.
  • Device characterized by said component part carried by said core being centered in relation to the core by means of a sleeve carried by the base plate thereof fitting in an enlarged cylinder bore of short length and coaxial with the cylinder bore containing the pick-up and the end thereof opposing said carriage.
  • Device characterized by the component part of the dash-pot carried by the carriage including at least one magnetic section attracted to said core by the magnetic field thereof for preventing accidental movement of the carriage away from said core.
  • a device wherein that one component part carried by said carriage has a cylindric protrusion extending outwardly from said carriage toward said magnet and the other component part has a cylindric protrusion extending outwardly from said magnet toward said carriage, one of said cylindrical protrusions being of a slightly greater diameter than the other of said cylindrical protrusions and each cylindric protrusion being arranged coaxially with the other to interact as a piston-cylinder arrangement when in engagement one with the other.
  • a device wherein at least a portion of said one component part is fabricated of magnetic material disposed to be attracted to said core by the magnetic field for preventing accidental movement of said carriage away from said core.
  • a device wherein there are stop means associated with said carriage remote from said motor for limiting movement of said carriage away from said motor.

Landscapes

  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Moving Of Heads (AREA)
US00264640A 1971-06-24 1972-06-20 Device for the displacement of magnetic read/write heads Expired - Lifetime US3827081A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR717123131A FR2142769B1 (enrdf_load_stackoverflow) 1971-06-24 1971-06-24

Publications (1)

Publication Number Publication Date
US3827081A true US3827081A (en) 1974-07-30

Family

ID=9079271

Family Applications (1)

Application Number Title Priority Date Filing Date
US00264640A Expired - Lifetime US3827081A (en) 1971-06-24 1972-06-20 Device for the displacement of magnetic read/write heads

Country Status (10)

Country Link
US (1) US3827081A (enrdf_load_stackoverflow)
BE (1) BE785236A (enrdf_load_stackoverflow)
CA (1) CA965182A (enrdf_load_stackoverflow)
CH (1) CH560444A5 (enrdf_load_stackoverflow)
DE (1) DE2230946A1 (enrdf_load_stackoverflow)
FR (1) FR2142769B1 (enrdf_load_stackoverflow)
GB (1) GB1377670A (enrdf_load_stackoverflow)
IT (1) IT956807B (enrdf_load_stackoverflow)
NL (1) NL7207923A (enrdf_load_stackoverflow)
SU (1) SU438206A3 (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030132A (en) * 1975-03-27 1977-06-14 Memorex Corporation Dual mode velocity servo control for a linear actuator motor
US4131924A (en) * 1977-10-03 1978-12-26 Burroughs Corporation Flexure mounted magnetic head positioner for high-speed translation
US4827162A (en) * 1987-03-02 1989-05-02 Unisys Corp. Controlled drag for magnet actuator
US5901008A (en) * 1993-12-15 1999-05-04 Seagate Technology, Inc Voice coil driven positioner for coarse and fine positioning of magnetic head in multi-track tape drive
US20030218390A1 (en) * 2002-05-22 2003-11-27 Story Huang Voice-coil motor for picking up chips

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2432581A (en) * 1943-07-26 1947-12-16 Milo F Miller Electrical switching apparatus
US2481398A (en) * 1945-06-29 1949-09-06 Armour Res Found Selector system for magnetic wire reproducers
GB1056888A (en) * 1964-10-08 1967-02-01 Flight Refueling Ltd Improvements in or relating to electro-magnetic actuators

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2432581A (en) * 1943-07-26 1947-12-16 Milo F Miller Electrical switching apparatus
US2481398A (en) * 1945-06-29 1949-09-06 Armour Res Found Selector system for magnetic wire reproducers
GB1056888A (en) * 1964-10-08 1967-02-01 Flight Refueling Ltd Improvements in or relating to electro-magnetic actuators

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030132A (en) * 1975-03-27 1977-06-14 Memorex Corporation Dual mode velocity servo control for a linear actuator motor
US4131924A (en) * 1977-10-03 1978-12-26 Burroughs Corporation Flexure mounted magnetic head positioner for high-speed translation
US4827162A (en) * 1987-03-02 1989-05-02 Unisys Corp. Controlled drag for magnet actuator
US5901008A (en) * 1993-12-15 1999-05-04 Seagate Technology, Inc Voice coil driven positioner for coarse and fine positioning of magnetic head in multi-track tape drive
US5978172A (en) * 1993-12-15 1999-11-02 Seagate Technology, Inc. Voice coil driven positioner for coarse and fine positioning of magnetic head in multi-track tape drive
US20030218390A1 (en) * 2002-05-22 2003-11-27 Story Huang Voice-coil motor for picking up chips

Also Published As

Publication number Publication date
IT956807B (it) 1973-10-10
CH560444A5 (enrdf_load_stackoverflow) 1975-03-27
FR2142769B1 (enrdf_load_stackoverflow) 1973-06-29
FR2142769A1 (enrdf_load_stackoverflow) 1973-02-02
NL7207923A (enrdf_load_stackoverflow) 1972-12-28
BE785236A (fr) 1972-10-16
SU438206A3 (ru) 1974-07-30
GB1377670A (en) 1974-12-18
DE2230946A1 (de) 1972-12-28
CA965182A (en) 1975-03-25

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