Study On The Deflector Of Laser Scanner On The Laser Imagesetter

The brushless direct current (DC) motor is a new type of motor combined with electrical phase change technology, which has advantages of good performance of its starting and adjusting rotation speed, long lifetime, higher reliability, sparkles in electrical phase change and low noise, etc.. The brushless DC current motors can be widely applied to electronical printing, aerospace, navigation, aviation, radio communication, test, measurement and mining, etc..The deflector of laser scanner on the laser imagesetter is the key part in the laser scanning imaging technology, and operating state of the laser scanner has an influence on quality of it. If the laser scanner is off normal function spurious images (e.g. stripe images) appear in scanning image. There are three factors to influence precision of the laser scanner, i.e. inertial of the shafting friction drag resistance of bearing and wind resistance introduced by irregular geometrical structure under operating at high speed.The letter in these factors is not ignorable in rotating shafting at high speed because of effect of it on power of the laser scanner. Alternative radial force generated by irregular geometrical parts rotating at high speed is put upon the shafting and makes the shafting shake radially. The stability (stable speed accuracy) of driving motor rotating of the deflector of laser scanner is required stringently and is up to 1.0417*10~5 in general. Study on the laser scanner is very important since fluctuate of rotating speed of the motor, wobble of the shaft of the laser scanner, tremble introduced by motor changing phase, shake generated out of dynamic balance, turbulence introduced by the deflector rotating at high speed have an influence on rotating shaft and light beam so as to decrease quality of the laser imagesetter.This paper describes principle and general design on rotating deflector of the laser scanner according to application. Theory on brushless DC motor is studied and structures of the mechanics and control system have been designed according to special requirements of the rotating laser scanner.The scanning motor developed has been tested synthetically in performance. The errors of system and parts of units of the laser imagesetter have been tested, analysed and connected in dynamic balance and also the errors of the laser scanner, reason and source for their generation, and other factors have been analysed and studied.