Hard disk drive construction and working:
Construction :
A hard disk drive is a sealed unit that a PC uses for nonvolatile data storage. Nonvolatile, or semi-permanent, storage means that the storage device retains the data even when no power is supplied to the
computer. A hard disk drive contains rigid, disk-shaped platters, usually constructed of aluminum or glass.
Hard Disk Drive Components:
1- Disk platter
2- Read/Write head
3- Head arm/Head slider
4- Head actuator mechanism
5- Spindle motor
6- Logic board
7- Air filter
8- Bezel
9- Cables & Connectors
1. Platters: A hard disk drive has one or more flat circular disk called platters. Platters are made of an Aluminum alloy, which provides both strength and light weight. Newer HDDs use glass and glass
ceramic platters. These platters are coated with magnetizable media coating which can store information magnetically.Two types of recording media used in HDD namely Iorn oxide media and Thin film media.
2. Read /Write Head: A hard disk drive usually has one read/write head for each platter surface, such that each platter has two sets of read/write heads - one for the top side and one for the bottom side.
These heads are connected, or ganged, on a single movement mechanism.
3. Head Actuator Mechanism: This mechanism moves the heads across the disk and positions them accurately above the desired cylinder. Two types of actuators are Stepper motor actuators and Voice coil actuators.
4. Head Arm/Head Slider: The arm on which the Read/Write head is located, and connects to the actuator.
5. Spindle Motors: The motor that spins the platters is called the spindle motor,because it is connected to the spindle around which the platters revolve. Spindle motors in hard disk drives are always connected directly; no belts or gears are involved. The spindle motor also must be precisely controlled for speed.
6. Logic Boards: Logic board with electronic components controls all these different parts of HDD. An intelligent circuit board is in built to the hard disk. It also acts as an interface between the hard disk drive and the computer.
7. Air Filters: Nearly all hard disk drives have two air filters. One filter is called the re circulation filter, and the other is called breather filter. These filters are permanently sealed inside the drive and are designed never to be changed for the life of the drive. The re circulation air filter is used to filter any particles dislodged from inside the drive such as scarp of the disk media.
8. Bezel: Front face plate provided on most of the HDD.
9. Most drives have at least these three types of connectors: Interface connector(s), Power connector and Optional ground connector.
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