| 摘要 |
PURPOSE:To obtain the automatic focusing device of an image forming device which scans on characters, etc., at the folding part of a thick book in a focusing state and prevents images from becoming out of focus, by sliding and control a distributed index type lens array or lens. CONSTITUTION:A light beam 6f from a light source 6b is reflected by an original 1, reflected by a mirror 6d through a lens 6c, and guided to a solid-state image pickup element 6e. The solid-state image pickup element 6e is arranged at a position which is conjugate optically to the top surface of platen glass 2. When the original 1 floats over the platen glass 2 like the folding part 1b of a thick book 1a, its original image is out of focus on the solid-state image pickup element 6e. The current out-of-focus extent is detected and the solid-state image pickup element 6e outputs a signal. When the original 1 coincides with the top surface of the platen glass 2 or separates floating, a signal is outputted to a lens position control circuit 7 and further to a solenoid 8. Then, the iron core of the solenoid 8 is slid and the lens array 4 is slid associatively in a supporting jig 9 as shown by an arrow 4a to focus even characters, etc., entered at the folding part 1b of the thick book 1a. |
