| 摘要 |
An electronic blackboard includes a writing sheet movable along a predetermined path and having a plurality of writing sections spaced apart one from another, reading means for optically reading the writing sheet, and recording means for recording information read by the reading means of a recording medium as a hard copy. In one aspect, the image information read by the reading means is subjected to thresholding operation to produce a binary image data, and a standard concentration pattern is provided on the recording sheet and it is used to automatically set a proper threshold level to be used in the thresholding operation. In another aspect, it is so structured that the writing sheet may be stopped with one of the plurality of writing sections in registry with or out of registry with a predetermined window. In a further aspect, the writing sheet is normally moved until the next adjacent writing section comes to be in registry with a predetermined window, but the writing sheet may be moved until its last writing section comes to be in registry with the window when so requested. In a still further aspect, the information written on the writing sheet may be recorded on a copy sheet with the information of one writing section on a copy sheet or with the information of two or more writing sections on a copy sheet.
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