Abstract: A light unit for a display device is used as a back light of an LCD panel and adapted to allow light entered from the side to exit in a perpendicular direction. The light unit includes a light source emitting white light; a light guide plate located at one side of the light source to transmit the light from the light source therethrough; a color dispersion sheet located opposite to the front surface of the light guide plate to refract the light transmitted through the light guide plate at different angles according to wavelength and to reflect the refracted light back into the light guide plate; and a diffraction pattern formed on at least one of the front surface and rear surface of the light guide plate to allow the light to pass through the color dispersion sheet to exit at the same angle.

Abstract: Disclosed herein is a light unit for a display device, which is used as a back light of a liquid crystal display(LCD) panel. This is adapted to allow light entered thereinto from the side to exit in a direction perpendicular to the light unit.

Abstract: A color corner of a projection system includes a dichroic filter having a flat plate type structure, thereby achieving an improvement in color separation characteristics while allowing easy manufacture of the dichroic filter. The projection system includes an illumination unit for separating an S-polarized light from a non-polarized white light, a polarized beam splitter for transmitting a selected one of the R, G, and B components of the light received from the illumination unit while reflecting the remaining two components of the incident light, and a flat plate type dichroic filter for defining different transmission and reflection optical paths for the separated two light components, respectively, thereby separating the two light components reflected by the polarized beam splitter.

Abstract: Disclosed is an apparatus for projection display using reflection type LCDs. The apparatus for projection display using reflection type LCDs according to the invention comprises an illuminating device including a lamp and a polarizing element for illuminating S wave or P wave, a color splitter/synthesizer, including the reflection type LCDs for providing an image corresponding to an inputted image and converting a polarizing state of incident light when reflecting the light, a retarder stack for differentiating the polarized state of a predetermined color from the incident light, and polarizing beam splitters composed of a material having a photoelastic constant less than 0.03×10−6 mm2/N at a wavelength of 589.3 nm and a minimum transmittance higher than 90% in transmitting the thickness of 25 mm at a wavelength ranged 0.42 &mgr;m-0.

Abstract: Disclosed is a color corner of a projection system including a dichroic filter having a flat plate type structure, other than a cube prism type structure, thereby being capable of achieving an improvement in color separation characteristics while allowing an easy manufacture of the dichroic filter, and thus, achieving an improvement in productivity.