Lighting unit, display device, and phosphor film
To provide a lighting unit which: does not greatly affect the design of a light guide plate; and has a long lifetime, high efficiency, and a wide color reproduction range by means of a phosphor. In view of the foregoing, the lighting unit of the present invention is constituted in such a manner that a phosphor bead or a phosphor film is arranged on at least one of the light irradiation plane of a light guide plate, the rear surface of the light guide plate, and the light incidence plane of the light guide plate. In addition, a phosphor film is constituted by using: a phosphor bead formed of a phosphor particle and a water-impervious material with which the phosphor particle is coated so that the particle is confined in the material; and a polymer film holding the phosphor bead.
1. A lighting unit comprising:
a light source that emits blue light;
a light guide plate through which light from the light source propagates so that the light is applied in a planar fashion;
a green phosphor layer that converts blue light into green light;
a red phosphor layer that converts blue light into red light, the red phosphor layer being separated from the green phosphor layer and arranged closer to the light source than the green phosphor layer;
wherein the green phosphor layer includes green phosphor beads dispersed in a base material, the green phosphor beads each containing a plurality of green phosphor particles coated with hydrophobic material;
the red phosphor layer includes red phosphor beads dispersed in a base material, the red phosphor beads each containing a plurality of red phosphor particles coated with hydrophobic material; and
the maximum value for the average particle size of the green phosphor particles and the red phosphor particles is less than about one-fifth the size of the phosphor beads.
2. A lighting unit according to claim 1 ;
wherein the green phosphor layer and the red phosphor layer are formed by printing the base material; and
an area density of the green phosphor beads and the red phosphor beads dispersed in the base material is inversely proportional to a radiant intensity distribution of the light source.
3. A lighting unit according to claim 1 ; wherein the phosphor particles are a chalcogenide compound.
4. A lighting unit according to claim 1 ; wherein the average particle size of the phosphor particles is less than about 10 μm.
5. A light unit according to claim 1 ; wherein a light pipe through which light from the light source propagates so that the light is applied in a linear fashion is arranged on a side of the light incidence plane of the light guide plate;
the red phosphor beads are dispersed in the light pipe which constitutes the base material; and
the green phosphor layer is arranged between the light pipe and the light incidence plane of the light guide plate.
6. A display device comprising;
a non-self light emitting display element;
a light source that emits blue light;
a light guide plate through which light from the light source propagates so that the light is applied in a planar fashion;
a green phosphor layer that converts blue light into green light; and
a red phosphor layer that converts blue light into red light, the red phosphor layer being separated from the green phosphor layer and arranged closer to the light source than the green phosphor layer;
wherein the green phosphor layer includes green phosphor beads dispersed in a base material, the green phosphor beads each containing a plurality of green phosphor particles coated with hydrophobic material;
the red phosphor layer includes red phosphor beads dispersed in a base material, the red phosphor beads each containing a plurality of red phosphor particles coated with hydrophobic material; and
the maximum value for the average particle size of the green phosphor particles and the red phosphor particles is less than about one-fifth the size of the phosphor beads.