| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a lighting device capable of achieving characteristics of rapidly increasing emission light intensity in accordance with emission angle increase by a simple method. <P>SOLUTION: A lighting device includes a substrate 1, an LED element 2, and a lens 4. A light emission surface 41 of the lens 4 includes a first light emission surface 41a and a second light emission surface 41b. A curve obtained by cutting the light emission surface 41 by a plane including an optical axis A has, on a boundary between the first light emission surface 41a and the second light emission surface 41b, a change point P at which a rate of inclination decreases discontinuously. An angle between the optical axis A and a line segment L connecting the change point P and a light emission center of the LED element 2 is approximately equal to an emission angle with the highest light intensity, among emission angles, when lights emitted from the light emission surface 41 are viewed for every emission angle. <P>COPYRIGHT: (C)2011,JPO&INPIT |
