What is a Magnetic Head?

Jason C. Chavis

A magnetic head is any device used with some sort of recording technique designed to apply information to a type of physical medium such as a tape or hard disk. The concept uses electromagnetism to cause a certain material to change its orientation in a viable manner that can be interpreted by a playback resource. Traditionally, magnetic heads are used with some sort of tape coated in iron oxide. Disk drives use a similar principle, but convert the magnetism into electrical current.

Magnetic heads are used with recording tape coated in iron oxide.
Magnetic heads are used with recording tape coated in iron oxide.

For tape recorders, a type of magnetic head stays in place as the tape is run along its surface. Two designs are used for this process: a fixed or rotating head. Fixed heads are generally used for audio recording, magnetically adjusting two or more channels along the length of the tape. The rotating head is used for video technology, laying down magnetized data at an angle along the length of the tape to make use of the full surface area.

Tape recorders use a magnetic head to read and record on tape.
Tape recorders use a magnetic head to read and record on tape.

A tape-based magnetic head uses a basic structure to control the electromagnetic energy utilized to store data on the iron oxide. The magnetic material is designed in a round or square shape with a hole, allowing air or some other material to act as an insulator. As the tape passes along the magnetic head, the electromagnetic energy magnetizes the iron oxide on the tape. Utilizing a wire coil connected to the device, it can either be used as a magnetic head reader or magnetic recording head. This means that the tape can either be read for data or have data placed upon its length for storage.

With hard drives, the magnetic head is designed very differently with a vastly different purpose. The magnetic head, composed of coil-wrapped ferrite, sits above the disk's surface producing a magnetic field. This field is concentrated into an electrical current. As the disk spins, the electromagnetic reaction creates electronic data to be stored for later use. Likewise, the current is used to read back the information.

Over the years, the magnetic head of hard disk technology has gone through many changes. During the early 1990s, metal-in-gap heads were invented that used a small piece of metal placed within the ferrite to help process more condensed pieces of information. In the early 2000s, heaters were added to the construction of hard disk to allow the magnetic heads to operate with additional disk platters. The heat generated from these devices helps saturate the disk with stronger magnetism, ensuring that the information is more securely stored.

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