| 摘要 |
PURPOSE:To provide an image forming device provided with an automatic focus detection means by which the focusing of a projected image formed on a screen surface or the surface of a recording medium is quickly performed with high accuracy and the excellent projected image is easily obtained. CONSTITUTION:The projected image illuminated by an illumination means is projected on the screen surface or the surface of the recording medium by a projecting lens 7 and a luminous flux separation means 8 is provided in an optical path between the projecting lens 7 and the screen surface. After a part of a luminous flux based on the projected image is separated through the means 8, it is formed to an image on the surface of a photodetector by an image forming lens 9, and the formed state of the projected image on the screen surface or the surface of the recording medium is judged by a judging means 21 by utilizing a signal obtained by the photodetector. By utilizing a signal obtained by the means 21, the position of the lens 7 on an optical axis is decided by a position decision means 22, and then in the case of performing the focusing of the projected image, the photodetector is arranged so that an image detection area may be positioned to be oblique to the projected image formed on the screen surface. |
