In 1973, IBM successfully developed a new type of hard disk IBM334, which is the ancestor of the hard disk we use today. IBM called it a Winchester hard disk. The composition of Winchester hard drives External structure (1) Interface The interface includes two parts: a power interface socket and a data interface socket. The power socket is connected to the power supply of the host to provide power for the normal operation of the hard disk. The data interface socket is the channel for data transmission and exchange between the hard disk data and the motherboard control chip. When using it, a data cable is used to connect it to the motherboard IDE interface or to the interface of other control adapters. It is often heard of 40-pin. , 80-core interface cable refers to the data cable, the data interface can be divided into PATA interface, SATA interface, SCSI interface. (2) Control circuit board Most of the control circuit boards use SMD welding, which includes spindle speed control circuit, magnetic head drive and servo positioning circuit, read-write circuit, control and interface circuit, etc. There is also a ROM chip on the circuit board, in which the solidified program can initialize the hard disk, execute power-on and start the spindle motor, power-on initial seek, locate and fault detection. High-speed data cache chips of varying capacities are also installed on the circuit board. (3) Fixed panel It is the front panel of the hard disk, which is combined with the bottom plate to form a sealed whole, which ensures the stable operation of the hard disk platter and mechanism. The most conspicuous thing on the panel is the product label, which is printed with the product model, product serial number, product, production date and other information. In addition, there is a vent hole whose function is to keep the internal pressure of the hard disk consistent with the atmospheric pressure. 2. Internal structure The internal structure of the hard disk consists of a magnetic head, a disk, a spindle, a motor, and other accessories. The magnetic head disk component is the core of the hard disk. It is packaged in the clean cavity of the hard disk and includes a floating head component, a head drive mechanism, a disk, These parts of the spindle drive device and the front read/write control circuit. 1. Magnetic head assembly This component is one of the most precise parts of the hard disk. It consists of three parts: a read-write head, a transmission arm, and a transmission shaft. The magnetic head is the most important and key part of the hard disk technology. It is actually a combination of multiple magnetic heads made by integrated technology. It uses a non-contact head and disk structure. After power is applied, it moves on the surface of the high-speed rotating disk. The gap between the discs is only 0.1 ~ 0.3um, so that a good data transfer rate can be obtained. At present, the flying height of the hard disk with a rotation speed of 7200RPM is generally lower than 0.3um, in order to facilitate the reading of larger signals with high signal-to-noise ratio, and to provide the reliability of the data transmission rate. 2. Magnetic head drive mechanism The hard disk seeks by moving the magnetic head, and moving the magnetic head requires the drive of this mechanism to be realized. The magnetic head drive mechanism is composed of an electromagnetic coil motor, a magnetic head drive trolley, and an anti-vibration device. The high-precision light magnetic head drive mechanism can drive and position the magnetic head correctly, and accurately locate the track specified by the system command in a short time. 3. Disk Disks are the carriers of hard disk storage data. At present, most hard disk disks use metal film materials. Compared with the discontinuous particle carrier of floppy disks, this metal film has the advantages of higher storage density, high remanence and high coercivity. In addition, IBM also has a material called "glass disc" as the disc substrate. Glass discs have better stability during operation than ordinary discs. It can be seen from the picture that the hard disk is completely flat and can be used as a mirror. 4. Spindle assembly The main shaft assembly includes main shaft components such as bearings and drive motors. With the expansion of hard disk capacity and the increase in speed, the speed of the spindle motor is also increasing. Some manufacturers have begun to adopt the liquid bearing motor technology of the precision machinery industry, which is conducive to reducing the working noise of the hard disk. Through this dissection of the hard disk, I believe that the reader has a certain understanding and understanding of the internal structure of the hard disk, saw what the head looks like, knows the surface of the disk is as smooth as a mirror, and understands how the hard disk is initialized and the seek is completed. . Of course, this dissection work is only a shallow disassembly. If you want to dissect and study the magnetic heads, disks, motors, spindles, etc., you need higher technical conditions and equipment. About hard drives The hard disk drive adopts a high-precision, light-weight head drive/positioning system. This system enables the magnetic head to move quickly on the disk surface, and can be accurately positioned on the track specified by the computer command in a very short time. At present, the track density has reached 5,400Tpi (tracks per inch) or higher; people are still studying various new methods, such as squeezing (or etching) patterns, grooves and spots on the disk as positioning and tracking marks , In order to increase the track density to the same as that of the optical disc, thereby greatly increasing the storage capacity while maintaining the advantages of high speed, high bit density and high reliability of the disk drive. The motors in the hard disk drive are all brushless motors. With the support of high-speed bearings, the mechanical wear is small, and they can work continuously for a long time. The high-speed rotating disk produces obvious gyro effect, so it is not suitable to move it when the hard disk is working, otherwise, it will increase the working load of the bearing. In order to store and read information at a high speed, the magnetic head of the hard disk drive has a small mass and low inertia. Therefore, the seek speed of the hard disk drive is significantly faster than that of a floppy drive and an optical drive. The hard disk drive head is integrated with the head arm and servo positioning system. The servo positioning system consists of a coil behind the head arm and an electromagnetic control system fixed on the bottom plate. Due to the limitation of the positioning system, the head arm can only move between the inner and outer tracks of the disc. Therefore, no matter whether it is turned on or off, the magnetic head is always on the disk; the difference is that the magnetic head stays in the disk start-stop area when the power is turned off, and the magnetic head "flies" above the disk when the power is turned on. Fiber Optic Field Connector,Fiber Optic Accessory,Optical Fiber Accessories,Optical Fiber Accessory Huizhou Fibercan Industrial Co.Ltd , https://www.fibercan-network.com
