Stanley Electric Co., Ltd

International Business Machines Corporation

Other

Koji Kawada

Masaru Suzuki

Yoji Oki

Yoshiteru Watanabe

Kazushige Ohta

Satoru Konishi

Takashi Obata

A polarized component is obtained with a high conversion efficiency in a light guide which produces one of the polarized components by having it transmitted. The light from a light source is incident to a light guide which comprises a plurality of light guide layers and reflected by the end surface to an interface between the light guide layers. The polarized component transmitting through the end surface is rotated in its polarization plane by a wave length plate and reflected by a reflecting plate for reentrance to the light guide at the end surface of the light guide toward the interface. The reentering light mostly transmits through the interface because the polarization plane is rotated. A reflected light polarized component is returned to the wave length plate and the reflecting plate, and directed back to the interface again. The polarized component transmitting through the interface is similarly transmitted and reflected in the next interface. The number of interfaces can be reduced by increasing the reflection of the polarized component reflected in the interface. For this purpose, the index of refraction in the direction along the axis of the reflected polarized component is increased by making the index of refraction of the light guide layer anisotropic.

Light guide device enhancing a polarized component and liquid crystal display device

The invention is intended to reduce the weight of the entire unit, make it compact and prevent the emitted light from being in dark and bright stripes in a light guide unit for a back light of a liquid crystal display device. Further, this invention allows a prism sheet having a larger apex angle to be used. To this end, the light guide unit comprises a plurality of light guide films laminated on the light guide member. The sloped surface which is opposite to the incident surface of the light guide unit is formed with grooves each having an inclination of an angle related to Brewster angle. A prism sheet is further disposed with the side having apexes oriented to the light guide unit to deflect the light emitted from the light guide unit.

Wedge shaped light guide providing enhanced polarized light to a

Light guide device enhancing a polarized component and liquid crystal

A surface light source apparatus is constituted such that an overhang portion overhanging a light source is provided on part of an end surface where the light source of an optical guide plate is arranged in such a manner that it is flush with the front surface of the optical guide plate and that an incident light control unit formed from a resin for diffusing and attenuating light is provided integratedly on at least an overhang portion side out of the overhang portion and the end surface of the optical guide plate, and accordingly light from the light source is transmitted through the overhang portion, radiated in an illumination direction, and diffused and attenuated by the incident light control unit to equalize the amount of light so that it can be used as illumination light. Thereby, the total area of the light emitting portions is increased.

Surface light source apparatus

Growing community of inventors

Kanagawa, Japan

Koji Kawada