Image processing apparatuses such as copying machines, scanning devices, and facsimile machines are provided with an image reading device that reads an image from a document.
An image reading device (document reading device) provided with a so-called ADF (automatic document feeder) has an image reading section (document reading section) that, in a resting state, reads a document image from a document being carried along a platen glass (read glass). At that time, there are cases where the document comes into contact with the platen glass, and the platen glass is stained by unfixed materials on the document. The stain produces streaks of noise in the obtained image data, with the result that the quality of the image is badly impaired.
In light of such a problem, for example, Japanese Laid-Open Patent Publication No. 307695/1997 (Tokukaihei 09-307695; published on Nov. 28, 1997) teaches providing a contact-preventing device for preventing documents from coming in contact with a platen glass, in order to prevent the platen glass from being stained.
However, the document coming into contact with the platen glass is not the only factor that causes stains, and the platen glass can also be stained by non-contact factors such as paper dust or dust. The technique described in the above publication (Tokukaihei 09/307,695) suffers from a drawback in that it cannot deal with these factors other than the contact factor.
On this account, once the platen glass is stained, users need to clean the platen glass before reading a document, either before starting the operation or by interrupting the operation. This requires labor and, in particular, causes an inconvenience to users in a hurry.