| 摘要 |
A lighting unit (10) can utilize a lens body (30) which is smaller in thickness and lighter in weight than a conventional lens body (30), and which can achieve efficiency of use of light comparable to or higher than efficiency achieved by the conventional lens body (30). The lighting unit (10) can include an LED light source (20), and a lens body (30) with a first side surface (30a) functioning as a light exiting surface having a substantially rectangular shape greater in width than in thickness, and a second side surface (30b) opposite the first side surface (30a). The LED light source (20) can be arranged to face the second side surface (30b) such that a ray of light emitted in a wide angle direction with respect to an optical axis (AX) of the LED light source (20) travels toward the front and rear surfaces of the lens body (30), and that a ray of light emitted in a narrow angle direction with respect to the optical axis (AX) enters the lens body (30) through the second side surface (30b). The lens body (30) can include a first optical system (31), a second optical system (32), and a third optical system (33). The first optical system (31) can include: a lens section (31a) formed on the front or rear surface of the lens body (30); a first light incident surface (31b) arranged in an optical path of the ray of light collected by the lens section (31a); a first total reflection surface (31c) arranged in an optical path of the ray of light having entered the lens body (30) through the first light incident surface (31b); and a second total reflection surface (31d) arranged in an optical surface of the reflected ray of light having reflected totally off the first total reflection surface (31c). The second optical system (32) can include: a second light incident surface (32a) formed on the second side surface (30b); a third total reflection surface (32b) arranged in an optical path of the ray of light collected by the second light incident surface (32a) and having entered the lens body (30); and a fourth total reflection surface (32c) arranged in an optical path of the ray of light having reflected totally off the third total reflection surface (32b). The third optical system (33) can include a third light incident surface (33a) for causing a ray of light emitted from the LED light source (20) in a wide angle direction with respect to the optical axis (AX) and in the direction of the width of the lens body (30) to enter the lens body (30), and a fifth total reflection surface (33b) for causing the ray of light having entered the lens body (30) through the third light incident surface (33a) to reflect totally to exit as a ray of light substantially parallel to the optical axis (AX) through an intermediate region between the central region (31e1) and the outermost region (31e2) of the first side surface (30a) functioning as the light exiting surface. An air layer for causing the ray of light collected by the lens section (31a) to pass therethrough is formed between the lens section and the first light incident surface (31b). |
