| 摘要 |
PURPOSE:To detect a focusing state of an image forming lens with high accuracy by providing a projection means and an illuminance detection means to the reader. CONSTITUTION:When it is discriminated that no contrast exists in a picture 1a as a result of discrimination of a video signal obtained by a video signal processing circuit 11 by a discrimination means 16 or that the contrast is low, a projection means 101 projects a pattern 6 onto a face of a picture 1a on an original platen 1. Then the pattern projected onto the face of the picture 1a is formed on a face of an image pickup means 4 by an image forming lens 3 and a video signal obtained from the means 4 is used to detect the focusing state of the image forming lens 3. In this case, an illuminance detection means 102 measures the lightness of the picture 1a on the original platen 1. Then an adjustment means 10 adjusts the lightness of the pattern projected from the projection means 101 in response to the lightness of the picture 1a. Thus, the detection accuracy of the focusing state of the image forming lens 3 is improved. |
