Abstract: All of LEDs 12a-12d are switched on in a case of illuminating a main display 21 mainly. Thus, each LED 12a-12d has a lighting region 22a-22d respectively, thereby illuminating the main display 21 entirely. Central LEDs 12b, 12c in LEDs 12a-12d are switched on in a case of illuminating a sub-display mainly. Thus, each LEDs 12b, 12c has a lighting region 22b, 22c respectively, thereby illuminating the sub-display 21b.

Abstract: All of LEDs 12a-12d are switched on in a case of illuminating a main display 21 mainly. Thus, each LED 12a-12d has a lighting region 22a-22d respectively, thereby illuminating the main display 21 entirely. Central LEDs 12b, 12c in LEDs 12a-12d are switched on in a case of illuminating a sub-display mainly. Thus, each LEDs 12b, 12c has a lighting region 22b, 22c respectively, thereby illuminating the sub-display 21b.

Abstract: To provide an assistant light source and a front-light emitting light to the light guide plate efficiently. A sectional shape of prism 14a in the center of light stick is isosceles triangle having a tip angle (T°) of 100° and a tilt angle (a1) of 40°. The depth of the prism 14a is D1 ?m. A sectional shape of prism 14b in a ¼ position from an end of light stick is triangle having a tip angle (T°) of 100° and a tilt angle (a2) of 34.8°. The depth of the prism 14b is D2 ?m. A sectional shape of prism 14c in an end of light stick is triangle having a tip angle (T°) of 100° and a tilt angle (a3) of 24.05°. The depth of the prism 14c is D3 ?m.

Abstract: An asymmetric prism sheet 15 has a plurality of projections 17 having prism shape on its surface. The projection 17 comprises a first inclined surface 17a having a relatively gentle slope (easy slope) and a second inclined surface 17b having a relatively steep slope (steep slope). A base angle 17d on the side of the second surface 17b is ?° and a base angle 17c on the side of the first surface 17a is ?°. In the case that the light enters into the asymmetric prism sheet 15, which has the above-mentioned structure, from the bottom surface 15a (light guide plate 11), the light is mainly emitted in the substantially vertical direction (a direction inclined by relatively small angle to the vertical direction) in the first inclined surface 17a (arrows X), and is mainly emitted in the inclined direction (a direction inclined by relatively large angle to the vertical direction) in the second inclined surface 17b (arrows Y).

Abstract: To provide an assistant light source and a front-light emitting light to the light guide plate efficiently. A sectional shape of prism 14a in the center of light stick is isosceles triangle having a tip angle (T°) of 100° and a tilt angle (a1) of 40°. The depth of the prism 14a is D1 ?m. A sectional shape of prism 14b in a ¼ position from an end of light stick is triangle having a tip angle (T°) of 100° and a tilt angle (a2) of 34.8°. The depth of the prism 14b is D2 ?m. A sectional shape of prism 14c in an end of light stick is triangle having a tip angle (T°) of 100° and a tilt angle (a3) of 24.05°. The depth of the prism 14c is D3 ?m.

Abstract: To increase an amount of the light that can be used for the display efficiently in the total amount of the emitted light in the liquid crystal display device having the surface lighting device such as the front-light. The light (a) becomes the light component of the linearly polarized light by passing the retardation plate (11a). In the reflective polarizer (11b), only the light (b) that is a component of the polarization axis of the reflective polarizer (11b) passes through the reflective polarizer (11b) to enter into the end portion of the light guide (12). The light that is a component other than the component of the polarization axis of the reflective polarizer (11b) is reflected on the reflective polarizer (11b). The light reflected on the reflective polarizer (11b) changes from the linearly polarized light to the circularly polarized light by passing through the retardation plate (11a).

Abstract: An object of the invention is to provide a surface illumination device and a display device using it, which can contribute to improvement of display qualities. A surface illumination device 10 comprising a light guide plate 1 for propagating incident light inside itself and reflecting the light at the reflecting prism face 1S to output the light from the light exit face. This further comprises: a polarizing plate 3 provided on the light exit face; and an anti-reflection film 4 provided on the polarizing plate 3. The reflecting prism face 1S extends so that a direction of electric vector's vibration of an s-polarized light component of a reflecting light ray caused by an incident light ray in a predetermined propagation direction is in parallel with a polarization axis of the polarizing plate 3, whereby a light efficiency can be improved.