Abstract: The invention described a thermal printer. The thermal printer has a supply reel, a take-up and a pair of motors. Each motor connects with the supply reel and the take-up reel, respectively. A detecting apparatus detects ribbon and the reel parameters while initializing the thermal printer. A memory stores a transforming table which can obtain the driving pulse width of each motor from a radius of the supply reel, a radius of the take-up reel and the ribbon tension. A control apparatus drive each motor with different pulse width according to parameters detected by the detecting apparatus and the transforming table. A thermal print head performs a printing process.

Abstract: A laser diode unit, having advantages of dissipating heat quickly, being capable of protecting itself from being destroyed by an incidental electrostatic or electric voltage, being effective to deal with the operations of aligning, positioning, adjusting, and being easy to be mass-produced. The laser diode unit includes a laser diode element for emitting laser light beam; a mold housing for securing the laser diode element thereon, laser light beams emitting from the laser diode element being capable of penetrating the mold housing; a collimating lens set disposed within the mold housing for collimating the light of the laser beam emitting from the laser diode element; and an adjusting means for driving the collimating lens set to move to and fro within a through bore formed in the mold housing.