Patent ID: 6839073
Filing Date: 2005-01-04
Classification: B41J,G02B

Abstract:
1. An image forming apparatus comprising: an image bearing member; at least one beam generation unit which emits a beam to scan the image bearing member; a galvano-mirror which reflects the beam emitted from the beam generation unit for the scanning and which rotates by an amount corresponding to a level of an inputted driving voltage to change a reflection angle, thereby adjusting a scanning position of the beam; a first digital/analog conversion unit into which digital data to continuously and finely adjust the reflection angle of the galvano-mirror is inputted and which outputs a voltage signal of a level corresponding to the digital data; a second digital/analog conversion unit into which digital data to stepwise and coarsely adjust the reflection angle of the galvano-mirror is inputted and which outputs the voltage signal of the level corresponding to the digital data; an amplification circuit which outputs the voltage of the level corresponding to the output voltage of the first digital/analog conversion unit and the output voltage of the second digital/analog conversion unit as a driving voltage to the galvano-mirror; a detection section which detects the scanning position of the beam in the image bearing member; a first control section which increases/decreases/controls an input value of the digital data with respect to the first digital/analog conversion unit in a state in which the input value of the digital data with respect to the second digital/analog conversion unit is set to a predetermined value so as to allow the galvano-mirror to rotate in a direction in which the scanning position detected by the detection section is within a predetermined position; and a second control section which shifts the input value of the digital data with respect to the first digital/analog conversion unit to the other limit value of the first digital/analog conversion unit and which shifts the input value of the digital data with respect to the second digital/analog conversion unit by one step, when the input value of the digital data with respect to the first digital/analog conversion unit changes by the first control section to reach one limit value of the first digital/analog conversion unit.