Patent Document ID: 5479262
Application ID: 08096981

Base Claim:
1. A digital image forming apparatus for reading and writing an image of a document, comprising: a document board on which the document is set; reading means for reading the document by scanning the document; an A/D converter for converting an analog signal which is read by the reading means to a digital signal; signal processing means for processing the digital signal, comprising, first detecting means for detecting the existence of a dark portion in the image of the document and judging the document to be a book document if the image of the document has said dark portion, based on the signal corresponding to at least two lines in a scanning direction or in a direction perpendicular to the scanning direction, and second detecting means for detecting a center portion of the document on the basis of a center dark portion of the signal of said at least two lines if the document is judged to be a book document; and writing means for writing the digital signal on a photoconductive element in relation to the detected center portion.

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Claim 4:
4. The digital document forming apparatus of claim 1, wherein the book document is arranged with a page spreading direction parallel to the scanning direction of the reading means, and the direction of the lines is parallel to the scanning direction.