| 摘要 |
PURPOSE:To form a clear and accurate latent image on a photosensitive body by substantially equalizing thermal expansion coefficients of a first lens plate and a base plate of an image forming device and arranging a second lens plate on the first lens plate so that the lenses may have greater depth of focus. CONSTITUTION:A first lens plate 3 is made of a material whose thermal expansion coefficient is substantially the same as that of a base plate 1 on which light emitting diode element arrays 2 of, for example, glass epoxy resin is to be placed. The termal expansion coefficient of the plate 3 is substantially the same as that of the plate 1. Therefore, in using as a light source of an electrophotographic printer, even when heat is applied to both the plate 3 and the plate 1, the plate 3 and the plate 1 expand with heat by quatities which are almost the same with each other, so that positional deviations are not generated between lenses 6 and the light emitting diode element arrays 2. As a result, lights to be emitted by light emitting diode elements 2a are formed into an accurate and clear image on a surface of a photosensitive body through the lenses 6 and a latent image of high quality is formed on the photosensitive body 5. |
