Hard disk number of heads to read data head is a key component, its main role is to be stored on the hard disc on the magnetic information into electrical signals to transmit,supply classification a
but it works is the use of special materials with the resistance value The principle of the magnetic field changes to read and write data on the disc, head to a large extent determine the quality of hard disc storage density.
Now more commonly used is GMR (Giant Magneto Resisive) giant magnetoresistive heads, GMR heads using better materials and magnetoresistive effect multi-layer film structure, the traditional head than before, and MR (Magneto Resisive) magnetoresistive heads more is sensitive to changes in the magnetic field can cause a relatively large resistance to change in order to achieve higher storage density. Head is hard to read and write on the disc in the working tool is the hard one of the most sophisticated parts.
Coil wrapped around the head is made on the core. Hard at work, head on a platter by sensing the rotating magnetic field changes to read data; by changing the magnetic field on the disc to write the data. To avoid head and disc wear, in working condition, the head suspended in the high-speed rotating disc at the top, rather than direct contact with the disc only after the power is off, heads will automatically return to a fixed location on the disc ( called the landing zone, where the disc does not store data,power supply
is the starting position the disc). Thin-film sensor (TFI) heads
In 1990-1995, the hard drive using TFI read / write technology. TFI head is actually winding core. Disc through the core in the winding when the induced voltage on the head. TFI read head will reach its capacity of why the limit is due to increased magnetic sensitivity in the same time, it’s writing ability has diminished. Anisotropic magnetoresistive (AMR) head AMR (Anisotropic Magneto Resistive) 90 mid, Seagate’s hard disk using the AMR head.
AMR TFI head to head with complete write operation, but with the magnetic thin section components as read. In the case of a magnetic field, thin section of the resistance with the magnetic field changes, and then have a very strong signal. Hard to decipher changes in the magnetic field polarity of the resistance change caused by the thin, improved read sensitivity. AMR head to further improve the density, and reduced component count. As the AMR film a certain amount of resistance change limits, AMR technology can support up to 3.3GB / square inch recording density, so the sensitivity of AMR heads, there are limits.sine wave This led to the development of GMR heads.
GMR (Giant Magneto Resistive, GMR) GMR heads inherited the TFI head and head in the use of AMR read / write technology. But it’s on the disk read heads for magnetic variation showed higher sensitivity. GMR head is 4-layer magnetic thin film conductive material and consisting of: a sensor layer, a non-conductive intermediate layer, a tie layer and a magnetic exchange layer.
GMR sensor sensitivity three times larger than AMR heads, they were able to improve the disc density and performance. The number of heads on hard disc drives in the number of positive and negative sides of the disc are stored with the data, so a disc corresponding to the two heads to work properly.
Such as the total capacity 80GB hard drive, a single platter 80GB disc, and that only one disc, the disc has a positive and negative data, the corresponding two heads;
and the same total capacity 120GB hard drive, using two disk film, only three heads, one side of a disc is not the head. Network hard disk “network drive” or “superior network (U) disk” is the user’s files stored on the Internet, user-friendly “carry” their files, user-friendly with his friends and family “share” their files , all operations on the page of our website to complete. No restrictions on file type.