How the disc stepper motor driver reads the data

1) Laser head assembly: including photocell, focusing lens and other components, with the running gear mechanism and guide rail and other mechanical components, in the energized state according to the system signal to determine, read the disc data and transmit the data to the system through the data tape. (2) Spindle stepper motor:

The driving force of the disc operation is provided by the fast data positioning function during the telling run of the disc reading process. (3) Disc holder: the disc carrier in the open and closed state.

4) Starting mechanism: control the entry and exit of the optical disc tray and the start of the spindle motor, when the power is on, the starting mechanism will make the servo mechanism including the spindle stepping motor and the head assembly of the laser are in a half-loaded state, and the laser head mainly includes: laser generator (also known as laser diode), semi-reflective prism, objective lens, lens and photodiode.

When the laser head reads the data on the platter, the laser light emitted from the laser generator passes through a semi-reflective prism and converges on the objective, which focuses the laser light into extremely small dots of light and hits it onto the disc. In this case, the reflective material on the disc will reflect the light back through the objective lens, and then onto the semi-reflective prism. In this case, since the prism is a semi-reflective structure, the beam does not completely penetrate it and return to the laser generator, but is reflected, passes through the lens, and reaches the photodiode.

Since the surface of the disc records data at uneven points, the reflected light will go in different directions. Signals shot in different directions are defined as "0" or "1", and the LEDs receive the data arranged in "0" and "1" and interpret them into the data we need. During the whole process of reading data by the laser head, tracing and focusing directly affect the error correction ability and stability of the optical drive.

Tracing is all about keeping the laser head correctly aligned with the track in which the data is recorded at all times. When the laser beam coincides with the orbit, the tracking error signal is 0, otherwise the tracking signal may be positive or negative, and the laser head will make appropriate adjustments to the attitude according to the tracking signal. If the tracking performance of the optical drive is very poor, there will be a phenomenon of reading data errors when reading the disk, the most typical is the phenomenon of skipping sound when reading the audio track.

The so-called focusing means that the laser head is able to accurately hit the beam onto the platter and receive the strongest signal. When the laser beam is reflected off the platter, it hits four photodiodes at the same time. They superimpose the signals and eventually form a focused signal.

This signal is 0 only if the focus is accurate, otherwise, it will send a signal to correct the position of the laser head. Focusing and seeking are the two most important properties of the laser head when working, and the optical drives we call good disc reading are products with excellent performance in these two aspects.

As far as I know, there is no stepper motor on the disc.

1. There are 2 voltages for optical drive power supply:

1) +12V, power supply to optical drive spindle motor and seek motor.

2) +5V, provide power to the optical drive circuit board.

The power supply voltage of the notebook optical drive is +5V, the spindle motor and seek motor and circuit board are all +5V.

2. Detailed information of L298N drives DC motor and stepper motor drive circuit; The motor speed control circuit (PWM signal) mainly adopts L298N, which can change the level of the chip control terminal through the IO input of the single-chip microcomputer, that is, the motor can be changed.

Forward and reverse, stop operation,