| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a position detecting technology that has a wide position detection range and able to detect a correct position even in a case where flag and photointerrupter have manufacturing variations. <P>SOLUTION: An image forming apparatus 30 for forming an image on recording paper S comprises a loop quantity detecting device 64 including: a photointerrupter 68 that has a light emitting part 71 for emitting light and a light receiving part 72, set opposite the light emitting part 71, for receiving light from the light emitting part 71, and that changes in output voltage according to an amount of light received by the light receiving part 72; a flag 69 that is reciprocately moved between the light emitting part 71 and light receiving part 72 and optically transparent. In the image forming apparatus 30, the flag 69 has such a shape that its thickness gradually changes in the direction in which light is emitted from the light emitting part 71 to the light receiving part 72. The apparatus detects the state of recording paper S according to the change in the output voltage of the photointerrupter 68, caused by the reciprocal movement of the flag 69. <P>COPYRIGHT: (C)2012,JPO&INPIT |
