The present invention relates to a sheet supply apparatus and image forming apparatus, and particularly relates to a sheet supply apparatus for supplying sheets to an image forming apparatus, and an image forming apparatus having the sheet supply apparatus.
A conventional sheet supply apparatus supplies a sheet with an image on one side (the front side) having to an image forming apparatus such as a photocopier, printer, facsimile, or a like to form an image on the other face (the back side), thereby reducing the number of sheets to conserve resources arid reducing an impact on the environment.
As an example of such a sheet supply apparatus, Japanese Patent Publication No. 10-293503 has disclosed an automatic document feeder (ADF) mounted on an image forming apparatus for determining whether one side of a sheet stacked on the ADF can be used. In this technique, when it is determined that the sheet can be printed, the sheet is transported from the ADF to a supply device disposed at a bottom of the image forming apparatus through a reuse sheet transporting path formed in the image forming apparatus in a direction opposite to the sheet feeding direction of the supply device, and then the sheets are stacked on the supply device.
Also, Japanese Patent Publication No. 02-8147 has disclosed a supply device comprising detecting means disposed at downstream of a sheet stacker for detecting whether one side of a sheet is blank, thereby sorting the sheet as a reusable sheet or not. With this technique, the sheet with at least one reusable blank side (hereafter referred to as “reuse sheet”) is automatically stacked with the blank side (reusable side) up.
Japanese Patent Publication No. 05-57966 has disclosed marking means for marking a side of the sheet with an image thereon to separate the sheet with an image thereon from the sheet which without an image. According to the technique disclosed in the Publication, without providing any special marking means, the image forming means can be used to mark the side of the sheet with an image thereon.
In Japanese Patent Publication No. 10-293503, the ADF and the supply device are arranged with the image forming apparatus in between. Therefore, it is necessary to arrange an internal configuration of the image forming apparatus to accommodate a reuse sheet transporting path from the ADF to the supply device through the image forming apparatus. Also, the reuse sheet is transported to be stacked within the supply device in a direction opposite to a direction that the reuse sheet is supplied from the supply device in the same path. Therefore, it is difficult to stack and supply the reuse sheet smoothly and quickly.
Also, in Japanese Patent Publication No. 02-8147, the disclosed supply device is used also as a sorting device for the reuse sheets, so the sheets need to first be stacked on a sheet stacker in the device before the sorting. Further, the device needs to have a discharge stacker for non-reusable sheets, thereby increasing a size of the supply apparatus.
Further, in Japanese Patent Publication No. 05-57966, the image forming apparatus has the marking means, so it is difficult to mark one side of the reuse sheet without changing the configuration of the image forming apparatus.
The present invention has been made in light of the above problems, and the first object of the invention is to provide a sheet supply apparatus and image forming apparatus wherein the reuse sheets can be stacked and supplied smoothly and speedily, while it takes a short period of time to replenish and exchange the sheets.
The second object of the present invention is to provide a compact sheet supply apparatus and an image forming apparatus having the sheet supply apparatus, wherein the reuse sheets can be stacked and supplied smoothly and speedily without changing the internal configuration of the image forming apparatus.
The third object of the present invention is to provide a sheet supply apparatus and an image forming apparatus having the sheet supply apparatus, wherein the reuse sheets can be loaded while being aligned, and also the side of the reuse sheet with no image thereon can be reliably used without mixing up with the side with an image thereon.
Further objects and advantages of the present invention will be apparent from the following description of the invention.