Dynamic magnetic information storage or retrieval – Head mounting – For shifting head between tracks
Reexamination Certificate
1998-03-25
2001-10-23
Davis, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For shifting head between tracks
Reexamination Certificate
active
06307717
ABSTRACT:
CLAIM FOR PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for METHOD AND DEVICE FOR FIXING COIL OF ACTUATOR IN HARD DISK DRIVE earlier filed in the Korean Industrial Property Office on the Mar. 25, 1997, and there duly assigned Ser. No. 10325/1997, a copy of which application is annexed hereto.
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to alignment of a voice coil in an actuator assembly of a hard disk drive, and more particularly to a method of fixing a voice coil in an actuator assembly to reduce distortion of the coil during insertion molding in order to maximize a recording density of a recording medium.
2. Related Art
Computers often include auxiliary memory storage units having media on which data can be written and from which data can be read for later use. Hard disk drives incorporating stacked, commonly rotated rigid magnetic disks are used for storage of data in magnetic form on the disk surfaces. Such hard disk drives typically include a motor drive spindle and associated actuator assembly for receiving and rotating a disk at a predetermined constant speed, a servo control mechanism for radially positioning a read/write transducer head in response to track position commands, and electronic circuitry for operating the motor to provide data to and read data from the disk. Some disk drives are designed with only one read/write transducer head while others are designed with a plurality of transducer heads for enabling data to be written onto and read from a plurality of corresponding disks.
High performance disk drive systems use a moving coil actuator assembly for positioning the transducer heads over a storage disk. Voice coil motor is adapted to move the actuator arm along a radial line with respect to the storage disk. Typical voice coil motor construction comprises a loop of coil (wire) containing numerous windings physically located between one or more permanent magnets. The windings are supported by and encircle a bobbin shaped in accordance with the permanent magnet dimensions. The wire loop of the voice coil contains electrical connections which enable the coil to carry a current for generating a magnetic field which interacts with the field of the permanently mounted permanent magnets to create necessary torque to move the actuator arm across the surface of the storage disk. The torque of a moving coil actuator is obtained by multiplying the force acting on the voice coil by a distance of the coil from a pivot axis. However, when the actuator is assembled, the distance of the coil from the pivot axis is inevitably shorter than designed, and the effective length of the coil is reduced due to the distortion of the coil. As a result, the torque acting on the voice coil motor is reduced, and the efficiency of the actuator is concomitantly diminished, which, in turn, decrease the performance and reliability of high performance disk drive.
SUMMARY OF THE INVENTION
Accordingly, it is therefore an object of the present invention to provide an improved voice coil motor for operations of a high performance disk drive.
It is also an object to provide a method for improving operation efficiency of a voice coil motor of an actuator assembly by reducing tolerance generated during assembling a voice coil.
It is further an object to provide an actuator assembly using metallic coil guides, and a bobbin for fixing the position of a voice coil in the actuator assembly to prevent distortion generated due to the difference in thermal expansion coefficients between the plastic bobbin and the metallic voice coil during insertion molding, and to enhance combining force between the coil and the bobbin.
These and other objects of the present invention may be achieved by an actuator assembly of a disk drive, comprising an actuator arm having a first distal end supporting a transducer head and a second distal end opposite to said first distal end supporting a movable voice coil section of a voice coil motor. The voice coil section comprises a coil, inner and outer bobbins positioned respectively at inner and outer sides of the coil, and a plurality of coil guides installed at respective corners of the inner bobbin for fixedly guiding the coil so as to prevent distortion due to difference in thermal expansion coefficients between the plastic bobbins and the coil during insertion molding in order to enhance a combining force between the coil and the bobbins. A gap of at least 0.5 mm is formed between the coil guides and the coil for separating the coil from the coil guides to prevent damages due to friction therefrom. The inner bobbin further comprises a plurality of guide holes perforated at corners for mounting the coil guides.
In accordance with another aspect of the present invention, the actuator assembly having a coil affixed by a series of steps of: preparing a mold for insertion molding an actuator arm having a first distal end supporting a transducer head and a second distal end opposite to the first distal end supporting a movable voice coil section of a voice coil motor; installing a plurality of coil guides on the mold, where respective corners of an inner bobbin supporting the coil are to be insertion molded, for fixing the position of the coil as the coil winds around the inner bobbin and restricting distortion of the coil and the inner bobbin; and insertion molding the actuator arm including the movable voice coil section, wherein the movable voice coil section is consisted of the inner bobbin, the coil wound around the inner bobbin but separated from the inner bobbin by a gap of 0.5 mm to prevent damages due to friction, and an outer bobbin for coil protection.
The present invention is more specifically described in the following paragraphs by reference to the drawings attached only by way of example.
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Bushnell , Esq. Robert E.
Davis David
Samsung Electronics Co,. Ltd.
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