| 摘要 |
PURPOSE:To prevent the information quantity of an object to be photographed, from being varied remarkably extending from a short range to a long range, by providing a lens which is allowed to have a difference in the light quantity to be applied in accordance with a distance. CONSTITUTION:As for a light emission diode (LED) 12, three LED chips 12A-12C are arranged in the vertical direction, and an emitted light beam is projected through a projection lens 14 and a cover lens 16. In such a case, the cover lens 16 is constituted of a plate part 16A positioned in the upper part than an optical axis of the projection lens 14, and a cylindrical lens part (plano-concave lens) 16B positioned in the lower part. Accordingly, in the cover lens 16, as for the projection light which is made incident on a long range side (plate part 16A), the light intensity is held, and as for the projection light which is made incident on a short range side (cylindrical lens part 16B), the magnification becomes larger and a projected image is elongated in the vertical direction, and the light intensity also becomes weaker. In such a way, it does not occur that the information quantity from the object to be photographed in a projection range is varied remarkably due to its distance. |
