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Bidirectional Dual-Velocity Accessing for a Disk Drive

IP.com Disclosure Number: IPCOM000046279D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Quinlan, WP: AUTHOR [+3]

Abstract

In a disk drive having a step cam for indexing the recording head to tracks on the disk, the access speed to different tracks can be optimized for each direction of access motion. When the cam follower associated with the head carriage is climbing up the cam, a higher torque and thus a lower stepping rate is required of the stepping motor moving the cam. When the cam follower is moving down the cam surface, a lower torque and a thus a higher stepping rate may be used by the cam-stepping motor. Accordingly, a microprocessor controlling the accessing motion may be programmed to select a higher stepping rate when the cam follower is moving down the cam.

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Bidirectional Dual-Velocity Accessing for a Disk Drive

In a disk drive having a step cam for indexing the recording head to tracks on the disk, the access speed to different tracks can be optimized for each direction of access motion. When the cam follower associated with the head carriage is climbing up the cam, a higher torque and thus a lower stepping rate is required of the stepping motor moving the cam. When the cam follower is moving down the cam surface, a lower torque and a thus a higher stepping rate may be used by the cam-stepping motor. Accordingly, a microprocessor controlling the accessing motion may be programmed to select a higher stepping rate when the cam follower is moving down the cam.

Fig. 1 shows a portion of the cam surface, while Fig. 2 shows the torque curve for the stepping motor driving the cam. When the cam follower is moving relative to the cam in the direction T1, the torque required of the stepping motor is T1 and the stepping rate is S1 in Figure 2. When the cam follower is moving in the direction T2 in Fig. 1, the required torque T2 is higher and the stepping rate S2 is lower (Fig. 2). Accordingly, a microprocessor controlling the stepping motor can drive the stepping motor at step rate S1, which is higher than S2, when the cam follower is moving down the cam rather than up the cam. Thus, accessing times can be less in one direction than the other by making use of the torque characteristic of the stepping motor.

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