In a related image forming apparatus, a recording sheet on which a desired image has been formed is discharged on a discharge tray provided on the left side or the right side outside an apparatus body. In case of this sheet discharge manner, it is necessary to secure, in addition to arrangement space for the apparatus body, arrangement space for the discharge tray. Therefore, recently, there is proposed an image forming apparatus of an inner discharge type, which discharges a recording sheet on which an image has been formed onto an inner discharge part provided in the apparatus body. In the inner discharge type image forming apparatus, since the upper portion of the inner discharge part is covered, a user cannot recognize visually a small-sized recording sheet unless a user does not look in the inner discharge part.
Therefore, for example, in an image forming apparatus disclosed in JP-A-2003-118918 (refer to paragraphs 0007 and 0014 to 0018, and FIGS. 1 and 5), a discharge tray provided between the lower surface of a reader and the upper surface of a printer is slanted so as to go down toward the downstream side in the sheet discharge direction. An abutment member is rotatably provided near the side surface on the downstream side in the sheet discharge direction of the discharge tray. The recording sheet is surely butted on the abutment member by increasing a transporting speed of a small-sized recording sheet or by changing a transporting path for small-sized recording sheet from a transporting path for large-sized recording sheet. According to the image forming apparatus disclosed in JP-A-2003-118918, the small-sized recording sheet slides down to the downstream side in the sheet discharge direction along the inclination of the discharge tray and is stopped by the abutment member, and the leading end portion of the recording sheet is aligned at the side surface on the downstream side in the sheet discharge direction of the discharge tray. Therefore, even if the user does not look in the discharge tray located between the reader and the printer, the user can readily recognize the small-sized recording sheet visually from the outside.
However, in the image forming apparatus disclosed in JP-A-2003-118918, when the recording sheet is to be taken out from the discharge tray, the abutment member must be rotated, which is troublesome. In case an image forming apparatus is configured such that the trailing end portion of the recording sheet is butted on the upstream side surface in the sheet discharge direction of the discharge tray to eliminate the abutment member, the user of the image forming apparatus does not notice the small-sized recording sheet placed in the inner part of the discharge tray, so that the small-sized recording sheets maybe accumulated on the discharge tray thereby to cause sheet transportation failure. Also, the user may forget to take out the small-sized recording sheet from the discharge tray.
Further, in the image forming apparatus disclosed in JP-A-2003-118918, the abutment member must be installed in the discharge tray. Alternatively, it is necessary to increase the transporting speed of the small-sized recording sheet or to change the transporting path of the small-sized recording sheet from that of the large-sized recording sheet in order to surely butt the small-sized recording sheet on the abutment member. Thus, the structure of the apparatus made complicated.