| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately detect the position of a toner pattern by preventing saturation of an output voltage from an optical sensor. <P>SOLUTION: While changing the value of a drive current flowing in a light emitting means, a light emission quantity determining means monitors a voltage output from a light receiving means, and thereby determines a quantity of light so as not to saturate the output voltage from the light receiving means. On the basis of a first drive current, a first output voltage, a second drive current and a second output voltage, the current value determining means determines a current value at which a target output voltage for preventing saturation of the output voltage is obtained. The first output voltage is obtained from the light receiving means when the first drive current is made to flow in the light emitting means. The second drive current is smaller than the first drive current. The second output voltage is obtained from the light receiving means when the second drive current is made to flow in the light emitting means. A target output voltage determining means determines from a first function a target output voltage from the light receiving means. <P>COPYRIGHT: (C)2009,JPO&INPIT |
