Optical system drive for image formation apparatus

Claim 1

An image formation apparatus, of the table type, for reproducing an image of a document, comprising: scanning means for scanning a surface of the document in order to produce a latent image of the document, said scanning means including a movable optical system including movable reflectors; a pulse motor for driving said movable reflectors; mode selecting means for selecting reduced scale, equal size or enlarged copying modes to change a scanning velocity during formation of the latent image; memory means for storing pulse motor drive data corresponding to each of the reduced scale, equal size or enlarged copying modes selected by said mode selecting means; open loop controlling means having a timer, and being connected to said pulse motor, said mode selecting means and said memory means, for reading out from said memory means the pulse motor drive data corresponding to the reduced scale, equal size or enlarged copying mode which is selected by said mode selecting means, to permit the pulse motor drive data to be set to said timer, for controlling a rotation velocity of said pulse motor in an open loop fashion in accordance with the mode selected by said mode selecting means and for judging, upon detection of a time-out signal from said timer, that the excitation time for the excitation phase of said pulse motor has elapsed, for reading out from said memory means the pulse motor drive data corresponding to the next excitation phase and then for setting said pulse motor drive data, read from said memory means, to said timer; hard copy reproducing means for reproducing said latent image of said document in hard copy form.