| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve problems of conventional LED lighting device that wide range irradiation is visible and dazzling when wide range irradiation and narrow range irradiation are performed simultaneously, and that power is consumed wastefully. <P>SOLUTION: The LED lighting device is composed of an LED chip of which a full width at half maximum of irradiation angle is not less than 90°, and a lens of which a shape of part of the cross section of a light emission face is ellipsoidal arc, and the angle between a direction in which lightness becomes maximum and a light axis direction of the LED chip is not less than 18° and not larger than 68°. By the above, the wide angle irradiation becomes invisible even if the wide range irradiation to a wall face and the narrow angle irradiation for a work are performed simultaneously. A ratio of lightness in a direction in which the lightness becomes maximum to that of light axis is not less than two times, the full width at half maximum of irradiation angle is not less than 5°and not larger than 30°, and a ratio of a radius of short axis of the ellipsoidal lens to a radius of long axis thereof is not less than 0.7 and not more than 0.9. Further, when the lighting device is used for a vehicle or a work, the direction in which the lightness becomes maximum can be changed by moving the lens. <P>COPYRIGHT: (C)2007,JPO&INPIT |
