This section provides a brief introduction to the typical fields where laser diodes can be applied.

The laser printer is attracting wide attention as an ideal printer, because it provides very clear high printing quality, allows high speed printing, and operates silently without producing noise.
The laser diode is finding wide use as the laser light source for the printer, because it meets the small size and low power consumption requirements.

Basic configuration
Fig. 1 shows the basic configuration of the printer.
The printer as a whole consists of signal control system, optical system and recording system.

a.Signal control system
The laser diode, modulated by the record signal, gives the pattern of dot signals to be printed in light ON/OFF form.

b.Optical system
In the optical system, the laser light from the laser diode is converted into parallel beams by the collimator lens. The beams are horizontally and vertically scanned by the polygon mirror and photosensitive material drum in rotation at a low speed.

c.Recording system
The role that the laser diode plays in the recording system is described in Fig. 2.

*1 The surface of the photosensitive material drum is uniformly charged.
*2 Then the drum is exposed to the laser beam. The charge in the exposed portion escapes, so an electrostatic latent image is formed.
*3 The toner pre-charged to reverse charge is brought into contact with the photosensitive material on which the electrostatic latent image was formed for development.
*4 A voltage is applied for discharge to transfer the toner to plain paper.
*5 Fixing is done by pressurizing and heating.
*6 The remaining toner is removed.
*7 The surface of the photosensitive material is discharged.