| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus where the status of a cassette unit including an extended cassette unit is surely returned even when the cassette unit is extended. <P>SOLUTION: In a period Δta until a next paper supply start command [second step] (ER7) is issued after a paper supply start command [second step](ER7) is issued and no paper exists in a paper supply optional cassette 515 at the second step, commands of at least a first step optional information status 1 request (SR2), a second step optional information status 2 request (SR6) to paper surface sensor information status request (SR8) are issued. Thus, an engine controller 602 detects information by the paper existence sensor 529 of the paper supply optional cassette 515 at the second step by the time the next paper supply start command [second step](ER7) is issued. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
