Design Features of the Zip Drive Head Drive
Unlike HDDs, the Zip drive uses a linear drive with a moving coil. There are two types of drive mechanisms for moving coil heads: linear and rotary. These types differ only in the physical arrangement of magnets and coils.
The drive with a moving coil is an electromagnet. Its design resembles that of a conventional loudspeaker. When a current of a certain polarity flows, the coil moves in or out of the gap of the permanent magnet. In Zip, a movable coil is rigidly connected to a block of heads and is placed in the field of a linear permanent magnet. The coil and magnet are not interconnected in any way: the movement of the coil is carried out only under the influence of electromagnetic forces.
The linear drive used in the Zip drive moves the heads in a straight line, strictly along the radius line of the disk. Its advantage is that when it is used, there are no azimuthal errors characteristic of a rotary drive, but there is a significant drawback: the head block in such a mechanism must be massive enough, and to control it, you need, accordingly, massive enough and, most importantly , powerful, engine.
Due to its “heavy weight category”, and, accordingly, the inability to work fast enough, the linear drive cannot be used in modern HDDs.
In the production of hard drives, a rotary drive is used, which works on the same principle as a linear one, but in it the ends of the head levers are attached to the moving coil. When the coil moves relative to the permanent magnet, the head movement levers rotate, moving the heads to the axis or to the edges of the disks. Due to its low weight, such a design can move with great acceleration, which can significantly reduce the data access time. The rapid movement of the heads is facilitated by the fact that the shoulders of the levers are made different – the one on which the heads are mounted has a large length.
The probability of failure of devices where a massive linear drive is used is much higher than that of devices with a rotary drive (respectively, the use of a linear drive in a Zip drive can also cause a malfunction such as a breakage of heads).