Lighting unit, display device, and phosphor film

• US 20060255711A1
• Filed: 04/06/2006
• Published: 11/16/2006
• Est. Priority Date: 04/12/2005
• Status: Active Grant

• Current Assignee: Dawncrest IP LLC (IP Edge LLC)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Fukuda, Tomoki, Kurihara, Makoto, Dejima, Norihiro
• Granted Patent: US 7,695,150 B2
• Time in Patent Office: Days
• US Class Current: 313/485
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/004 Scattering dots or dot-like elements, e.g. microbeads, scattering particles, nanoparticles

Abstract

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.

Claims

1. A lighting unit comprising:

a light source;

a light guide plate through which light from the light source propagates so that the light is applied in a planar fashion; and

a phosphor layer including a phosphor bead formed by coating a surface of a phosphor particle with a hydrophobic material and a base material holding the phosphor bead,

wherein the phosphor layer is arranged on at least one of a light irradiation plane of the light guide plate, a rear surface of the light guide plate, and a light incidence plane of the light guide plate.

2. A lighting unit according to claim 1, wherein the phosphor layer is formed by printing the base material into which the phosphor bead is dispersed on a light emission plane of the light guide plate.

3. Alighting unit according to claim 1, wherein an area density of the phosphor bead dispersed into the base material is inversely proportional to a radiant intensity distribution of the light source.

4. A lighting unit according to claim 1, wherein the phosphor layer is mixed with a second phosphor bead formed by coating a surface of a second phosphor having a luminous wavelength different from that of the phosphor particle with a hydrophobic material at a predetermined ratio.

5. A lighting unit according to claim 4, wherein:

the light source comprises a blue light source; and

the phosphor layer includes a red phosphor layer converting blue light into red light and a green phosphor layer converting blue light into green light.

6. A lighting unit according to claim 4, wherein:

the light source comprises an ultraviolet light source and a blue light source; and

the phosphor layer includes a green phosphor film converting ultraviolet light into green light and a red phosphor film converting ultraviolet light into red light.

7. A lighting unit according to claim 4, wherein a phosphor bead emitting light having a shorter wavelength of the phosphor bead and the second phosphor bead is arranged to be closer to the light source than the other phosphor bead.

8. A lighting 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 phosphor layer is arranged in the light pipe; and

the phosphor layer is mixed with the phosphor bead and a second phosphor bead formed by coating a surface of a second phosphor having a luminous wavelength different from that of the phosphor particle with a hydrophobic material at a predetermined ratio.

9. A lighting 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 phosphor bead is dispersed into the light pipe; and

a phosphor film containing a second phosphor bead formed by coating a surface of a second phosphor having a luminous wavelength different from that of the phosphor particle with a hydrophobic material is arranged between the light pipe and the light incidence plane of the light guide plate.

10. A display device comprising:

a non-self light emitting display element;

a light source;

a light guide plate through which light from the light source propagates so that the display device is irradiated with the light; and

a phosphor layer including a phosphor bead formed by coating a surface of a phosphor particle with a hydrophobic material and a base material holding the phosphor bead,

wherein the phosphor layer is arranged on at least one of a light irradiation plane of the light guide plate, a rear surface of the light guide plate, and a light incidence plane of the light guide plate.

11. A phosphor film comprising:

a phosphor bead formed by coating a surface of a phosphor particle with a hydrophobic material; and

a polymer film holding the phosphor bead.

12. A phosphor film according to claim 11, wherein the phosphor bead is dispersed into the polymer film.

13. A phosphor film according to claim 11, wherein the phosphor bead is held on the polymer film via a binder.

14. A phosphor film according to claim 13, wherein the phosphor bead comprises multiple phosphor beads, and the beads are arranged in a form of a single layer on the polymer film in such a manner that the beads do not overlap each other.

15. A phosphor film according to claim 11, which is mixed with a translucent bead containing no phosphor at a predetermined ratio.

16. A phosphor film according to claim 11, which is mixed with a second phosphor bead formed by coating a surface of a second phosphor having a luminous wavelength different from that of the phosphor particle with a hydrophobic material at a predetermined ratio.