Patent ID: 7639274
Filing Date: 2009-12-29
Classification: G02B

Abstract:
1. An image forming apparatus comprising: a plurality of latent image carriers; a plurality of exposure units each provided in correspondence to the respective latent image carriers, each of the exposure units including a light source and a oscillation mirror, and forming a latent image on the latent image carrier by deflecting a light beam from the light source into a deflected light beam by means of the oscillation mirror in oscillations and scanning the deflected light beam on the latent image carrier; a drive unit which applies a drive signal having a predetermined drive frequency to each oscillation mirror to drive the oscillation mirror; an adjusting unit which adjusts resonant frequencies of the oscillation mirrors, respectively; a controller which controls the adjusting unit in a manner to match all the resonant frequencies of the oscillation mirrors substantially with the drive frequency; and a plurality of developing units, each provided in correspondence to the respective plurality of latent image carriers, forming a plurality of different color toner images by developing the latent images with different color toners, respectively, wherein a color printing operation or a monochromatic printing operation is selectively performed, the color printing operation being of forming a color image by forming the different color toner images by means of the developing units and superimposing the different color toner images on each other on a transfer medium, the monochromatic printing operation being of forming a monochromatic image by forming a toner image by means of one of the developing units for a specific color of the plurality of colors and transferring the toner image to a transfer medium, wherein the drive unit is configured to vary the drive frequency of the drive signal, wherein the controller controls the adjusting unit in the execution of the color printing operation in a manner to match all the resonant frequencies of the oscillation mirrors substantially with the drive frequency, or controls the drive unit in the execution of the monochromatic printing operation in a manner to match the drive frequency of the drive signal substantially with the resonant frequency of an oscillation mirror corresponding to the specific color, and wherein when the color printing operation is executed, the controller performs an adjustment process to match all the resonant frequencies of the oscillation mirrors substantially with the drive frequency prior to the color printing operation, or when the monochromatic printing operation is executed, the controller does not perform the adjustment process.