Optical unit, backlight device, liquid crystal module and liquid crystal display apparatus

1. An optical unit for use in a backlight device of a liquid crystal display apparatus, comprising:

a light-diffusing component to diffract incident light; and

a first light-collecting component having a plurality of microlenses each having a shape of a hemisphere- or semi-oval-like protrusion on a light-emitting side of the first light-collecting component,

wherein the light-diffusing component and the first light-collecting component are provided in this order on an optical path of light emitted from a light source of the backlight device, and

the light-diffusing component includes:

a light-diffusing section having a first surface that faces the light source and an opposite second surface, the light-diffusing section being made of a material that is a transparent resin with a light-diffusing agent dispersed in the resin or a mixture of at least two types of resin which are hardly mixed with each other;

a first prism section provided on the first surface, having a plurality of prisms each having a cross section like teeth of a saw and a summit protruding towards the light source;

a second prism section provided on the second surface, having a plurality of prisms each having a cross section like teeth of a saw and a summit protruding in an opposite direction of each prism of the first prism section,

a light-diffracting component having a plurality of prisms provided on a light-emitting side of the light-diffracting component, each prism of the light-diffracting component having a cross section like teeth of a saw and a summit protruding in the opposite direction of each prism of the first prism section; and

a second light-collecting component having a plurality of microlenses each having a shape of a hemisphere- or semi-oval-like protrusion on a light-emitting side of the second light-collecting component,

wherein the light-diffusing section, the first prism section, and the second prism section are arranged in a manner that the light emitted from the light source is incident on the first prism section and diffracted in a direction orthogonal to a slope of each prism of the first prism section, the light diffracted by the first prism section is diffused inside the light diffusing section, and among beams diffused inside the light-diffusing section, beams incident on the second prism section at a specific angle are diffracted in a direction orthogonal to the light-diffusing section whereas other beams incident on the second prism section at angles different from the specific angle are reflected by the second prism section, and

wherein the light-diffracting component and the second light-collecting component are provided in this order on an optical path of light emitted from the first light-collecting component.

2. The optical unit according to claim 1 further comprising a polarization splitting component on an optical path of light emitted from the second light-collecting component, the polarization splitting component splitting incident light into a first linearly polarized light and a second linearly polarized light that is orthogonal to the first linearly polarized light, the first linearly polarized light being allowed to pass through the polarization splitting component, the second linearly polarized light being reflected by the polarization splitting component.