Is the internal structure and principle of a computer hard drive the same as an optical drive?

Not the same.

1. The internal structure of the hard disk is divided into: heads, tracks, sectors, and cylinders.

Magnetic head: The magnetic head is the most expensive component in the hard disk, and it is also the most important and critical part of the hard disk technology. The traditional magnetic head is an electromagnetic induction head that combines reading and writing. However, reading and writing on a hard disk are two completely different operations. Therefore, this two-in-one magnetic head must take into account both reading and writing when designing. These two characteristics have resulted in limitations in hard drive design. The MR heads (Magnetoresistive heads), that is, magnetoresistive heads, use a separate magnetic head structure: the write head still uses a traditional magnetic induction head (MR heads cannot perform writing operations), and the read head uses a new MR head. The so-called inductive writing and magnetoresistive reading. In this way, the different characteristics of the two can be optimized separately during design to obtain the best read/write performance. In addition, the MR head senses the signal amplitude through resistance changes rather than current changes, so it is very sensitive to signal changes, and the accuracy of reading data is also improved accordingly. And since the read signal amplitude has nothing to do with the track width, the track can be made very narrow, thereby increasing the disk density to 200MB per square inch, while using traditional magnetic heads can only reach 20MB per square inch. This is also the case with MR heads. The main reason why it is widely used. MR magnetic heads have been widely used, and GMR magnetic heads (Giant Magnetoresistive heads) made of materials with a multi-layer structure and better magnetoresistive effect have gradually become popular.

Tracks: When the disk rotates, if the heads remain in one position, each head will draw a circular track on the surface of the disk. These circular tracks are called tracks. These tracks are invisible to the naked eye because they are just magnetized areas on the disk that are magnetized in a special way. The information on the disk is stored along such tracks. Adjacent tracks are not immediately adjacent to each other. This is because when the magnetized units are too close to each other, the magnetism will affect each other, and it will also make it difficult for the magnetic head to read and write. A 1.44MB 3.5-inch floppy disk has 80 tracks on one side, while the track density on a hard disk is much greater than this, usually with thousands of tracks on one side. The magnetic track is generally magnetized by the magnetic head rapidly switching the positive and negative poles to change the 0 and 1 represented by the track.

Sector: Each track on the disk is divided into several arc segments. These arc segments are the sectors of the disk. Each sector can store 512 bytes of information. The disk drive When reading and writing data to disk, units are sectors. 1.44MB 3.5-inch floppy disk, each track is divided into 18 sectors.

Cylinder: A hard disk is usually composed of a set of overlapping platters. Each disk is divided into an equal number of tracks and is numbered starting from "0" on the outer edge. Tracks with the same number form A cylinder is called the cylinder of the disk. The number of cylinders on a disk is equal to the number of tracks on one side of the disk. Whether it is a double disk or a single disk, since each disk has its own unique magnetic head, the number of disks is equal to the total number of heads. The so-called CHS of the hard disk is Cylinder (cylinder), Head (head), and Sector (sector). As long as the number of CHS of the hard disk is known, the capacity of the hard disk can be determined. The capacity of the hard disk = number of cylinders * number of heads * Number of sectors*512B.

2. Internal structure of the optical drive:

(1) Laser head assembly: including photoelectric tubes, focusing lenses and other components, together with mechanical components such as operating gear mechanisms and guide rails. In the power-on state, it determines and reads the disc data according to the system signal and transmits the data to the system through the data tape.

(2) Spindle motor: the driving force for the operation of the optical disc, which provides fast data positioning function during the high-speed operation of the optical disc reading process.

(3) Disc tray: the disc carrier in the open and closed state.

(4) Starting mechanism: Controls the entry and exit of the disc tray and the starting of the spindle motor. When running with power, the starting mechanism will put the servo mechanism including the spindle motor and the laser head assembly in a semi-loaded state. .