| 摘要 |
PURPOSE:To detect a focal distance pure-electrically, by constituting a lens of a photodetecting element for photodetecting the reflected rays from a lens and an object to be photographed, of a liquid crystal, and providing a feeding means for variably controlling the focal distance. CONSTITUTION:Lenses 1, 1' and a glass plate 2 are connected in one body through a spacer 4 by sealing a space between the glass lenses 1, 1' whose radius of curvature is different from each other, and the glass plate 2, with a TN liquid crystal 3. On the inside surface of the lenses 1, 1' and the plate 2, a transparent electrode is provided as a feeding means for the liquid crystal 3. A liquid crystal lens 21 is fixed on the optical axis together with a polarization plate, and a focal distance of polarization transmitted when an electric field is applied is variably controlled. Accordingly, an image of an object to be photographed can be formed on a photodetecting element 6 by adjusting the applied electric field, and a focused clear image of an object to be photographed is obtained on a film surface 10 by generating a focusing signal corresponding to a value of the applied electric field in said case, moving a photographing lens 9, and forming the image of the object to be photographed, on the film surface 10. |
