Illumination apparatus for display device using hologram-based light guide plate (LGP)
View Patent ↗An illumination apparatus and method for a display device designed such that light is incident on a hologram or hologram pattern at an angle for which diffraction efficiency is the highest. The illumination apparatus includes at least one point light source which emits light and a light guide plate (LGP) which has the at least one point light source disposed on a side thereof and a hologram pattern on a top surface which permits the light incident from the point light source to exit from the top surface. The side of the LGP facing the point light source is inclined such that the light is incident obliquely on the hologram pattern at an altitude angle which provides high diffraction efficiency.
1. An illumination apparatus for a display device, comprising:
at least one point light source that emits light;
a light guide place (LGP) comprising a first surface on which a hologram pattern is formed, a second surface which faces the first surface, and a third surface which faces the at least one point light source; and
a diverging refractive lens which is formed on the third surface and divergently refracts the light emitted from the at least one point light source so that the light divergently refracted by the diverging refractive lens is incident obliquely on the first and second surfaces,
wherein the diverging refractive lens has a refractive index different from a refractive index of the LGP.
2. The apparatus of claim 1 , wherein the refractive index of the diverging refractive lens is greater than the refractive index of the LGP.
3. The apparatus of claim 1 , further comprising a second hologram pattern which is formed on the second surface.
4. The apparatus of claim 3 , further comprising:
a reflector which is disposed to face the second surface and reflects light exiting out through the second surface onto the first surface.