JPH02270170A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a moment on an actuator in principle wherever it is revolved by holding an FPC in order to make both ends of its bend lie along an outer wall and a supporting part. CONSTITUTION:A magnetic head 1 is fitted to the rotary type actuator 2, and is optionally movable to a prescribed position on a magnetic disk 3. The outer wall 5 of an actuator movable part and the supporting part 6 opposite to this outer wall are formed with cylindrical planes which are coaxial with a revolving center of the actuator, and are held in order to make both ends of the bend 7 lie along the FPC outer wall 5 and supporting part 6. Consequently, the radius of the bend 7 of the FPC is always constant, and its resiliency is always directed toward the revolving center of the actuator 2. By this method, the moment to act on the actuator from the FPC always is eliminated in principle.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to the structure of a flexible wiring board for a magnetic disk device.

[Conventional technology]

Conventionally, in a magnetic disk device, flexibility is required when wiring a magnetic head to a rotary actuator 2 to which a magnetic head 1 is attached, and therefore a flexible wiring board (hereinafter referred to as rFPC) is used. ) has been used. For example, as shown in FIGS. 2(a) and 2(b), both ends of the flexible portion are in contact with the outer wall 5 of the actuator movable portion and the plane of the opposing support portion, and as the actuator rotates, the flexible portion Bending and stretching are repeated on the upper and supporting planes. Further, in US Pat. No. 4,476,404, as shown in FIG. 3, the shape of the bent portion of the FPC is conical and the virtual apex of the cone coincides with the rotation center O of the actuator. [Problems and Objectives to be Solved by the Invention] However, in the former example of the prior art, as shown in FIG. 2(b), as the actuator rotates, the radius R of the bending portion of the FPC increases to R2, and the reaction forces F1 and F2 applied to the actuator movable part accordingly, and the distance 11111. between the point of application of the force and the center of rotation. 12 also changed, and as a result, the moment acting on the actuator also changed. With the recent increase in the capacity and speed of magnetic disk drives, there is a need for actuators with higher speed and higher precision, but the above-mentioned change in moment becomes a factor that hinders this. In particular, the voice coil motor (V
When using VCM), this change in moment makes it very difficult to determine the speed and position of the VCM. In addition, in the latter example, which was devised to avoid this, the moment moving to the actuator moving part is almost constant and its value is very small, but because it is conical, it requires space in the thickness direction of the drive. , it cannot be used in thin magnetic disk devices, and since the unfolded shape is arcuate, there is a problem that the bent part cannot be taken in the direction where it is most resistant to bending as a material for FPC steel foil. there were. Therefore, in the present invention, the change in moment due to FPC due to rotational movement of the rotary actuator is eliminated,
Another object of the present invention is to provide a magnetic disk device in which the flexible space of the FPC is reduced. [Means for Solving the Problems] A magnetic disk device of the present invention includes a magnetic head and a rotary actuator to which the magnetic head is attached, and a magnetic disk drive using a flexible wiring board for wiring to the movable part of the actuator. In the disk device, an outer wall of the actuator movable part and a flexible wiring board support part facing the outer wall have a cylindrical surface coaxial with the actuator rotation center, and the flexible wiring board is connected to the outer wall and the support part. It is characterized by being held so that both ends of the bent portion are along. [Operation] According to the above structure of the present invention, the radius of the bending part of the FPC is always constant and the reaction force is always directed toward the rotation center of the actuator, so in principle, a moment acting on the actuator from the FPC always exists. do not. [Embodiment] FIG. 1 shows a plan view of an embodiment of the present invention. The magnetic head 1 is attached to a rotary actuator 2, and can be moved to a desired position on the magnetic disk 3. In the example shown in this figure, the actuator is driven by VCM4. The outer wall 5 of the actuator movable part is a cylindrical surface having the same center as the rotation center thereof, and the supporting part 6 of the FPC is also a cylindrical surface having the same center as the actuator rotation center. There is. The bent portion 7 of the FPC is located between the two cylindrical surfaces, and both ends thereof are along the respective cylindrical surfaces. Therefore, even if the actuator rotates, the radius R of the arc of the bending portion is always constant, and a reaction force of a constant magnitude is always perpendicular to the outer wall of the movable portion. [Effects of the Invention] As described above, according to the present invention, the outer wall of the actuator movable part and the FPC support part facing the outer wall,
The FPC has a cylindrical surface that is coaxial with the rotation center of the actuator, and the FPC is held so that both ends of its bent portion are along the outer wall and the support portion, so that the f-ment acting on the movable portion of the actuator is In principle, this does not occur no matter what position the actuator rotates, and it does not apply torque to the motor that drives the actuator.
This has the effect of improving actuator positioning accuracy and speed stability during seek. Furthermore, not only when a VCM is used to drive the actuator, but also when a stepping motor is used, exactly the same effect can be obtained. Further, even if the FPCO width increases due to an increase in the number of wiring lines, according to the present invention, the space occupied in the planar direction of the drive does not increase, and higher density wiring becomes possible.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the magnetic disk device of the present invention. FIG. 2(a) is a plan view of a conventional embodiment. Figure 2(b) is an enlarged view of the same FPC installation part. FIG. 3 is a perspective view of another conventional embodiment. 1... Magnetic head 2... Actuator 3... Magnetic disk 4... VCM 5... Actuator - movable part outer wall 6... FP
C support part 7... FPC bending part and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki Ike 1 person S actu 1-
'? 'l'i+W%@ Figure 1 Figure 2 (CL) Figure 2 (b)

Claims (1)

[Claims] (1) In a magnetic disk drive having a magnetic head and a rotary actuator to which the magnetic head is attached, and using a flexible wiring board for wiring to the actuator movable part, an outer wall of the actuator movable part and the outer wall A flexible wiring board support portion facing the holder has a cylindrical surface coaxial with the rotation center of the actuator, and the flexible wiring board is held such that both ends of its bent portion are along the outer wall and the support portion. magnetic disk device.