| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a heat fixing device configured such that a cam is stopped at a required position at all times, a nip width is speedily and reliably adjusted so as to be optimum for a paper type and thickness, and to provide an image forming apparatus having the heat fixing device. <P>SOLUTION: The heat fixing device includes: a fixing member, a pressure member, a means for varying the width of the nip by changing a pressing force through the rotation of the cam 1; a drive motor for rotating and driving the cam 1; and a position detecting means for detecting the rotated position of the cam 1. The position detecting means includes a transmission type sensor and a shield filler 2. The shield filler 2 has blocking blades 42 for blocking light received by the transmission type sensor. The blocking blades 42 are disposed so as to differ in phase between the shield fillers 2A and 2b. On the basis of the number of rotations switched between an on-state and an off-state of a signal from a transmission type sensor, which is changed by intersecting light received by the transmission type sensor, the rotated position of the cam 1 is detected. The image forming apparatus has the heat fixing device. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
