Light unit using point light source, and liquid crystal display using the same light unit

A light unit, comprising:

• at least one point light source;
• at least one columnar light guide that receives light emitted from said point light source, through an end thereof, and reflects and refracts the received light while guiding it in a longitudinal direction thereof, to emit generally band-shaped light through a side surface thereof;
• and
• a rectangular plate-shaped light guide that receives light emitted from said at least one columnar light guide through a facet thereof, and reflects and refracts the light received through the facet using a prism surface having recesses and projections formed thereon and forming a plurality of linear parallel ridge lines inclined through a predetermined angle from the longitudinal direction of said columnar light guide, so that planar light is emitted from a light applied surface of the plate-shaped light guide which is opposite said prism surface,
• wherein each said point light source is arranged only at an end of said facet of said at least one columnar light guide at which the angle between a direction of light emitted from said point light source and said ridge lines on said rectangular plate-shaped light guide is acute, such that said ridge lines incline away from said point light source.

A liquid-crystal display, comprising:

• a point light source;
• a columnar light guide that receives light emitted from said point light source through an end thereof, and reflects and refracts the received light while guiding it in a longitudinal direction thereof, to emit generally band-shaped light through a side surface thereof;
• a rectangular plate-shaped light guide that receives light emitted from said columnar light guide through a facet thereof, and reflects and refracts the light received through the facet using a prism surface having recesses and projections formed thereon and forming a plurality of linear parallel ridge lines inclined through a predetermined angle from the longitudinal direction of said columnar light guide, so that planar light is emitted from a light applied surface of the rectangular plate-shaped light guide which is opposite said prism surface;
• and
• a liquid-crystal panel arranged opposite the prism surface of said plate-shaped light guide,
• wherein said point light source is arranged only at an end of said facet of said columnar light guide at which the angle between a direction of a light emitted from said point light source and said ridge lines on said rectangular plate-shaped light guide is acute, such that said ridge lines incline away from said point light source, and wherein the point light source, the columnar light guide and the rectangular plate-shaped light guide form a light unit that is used as a front light.