Photoluminescent sheet

Abstract

A photoluminescent sheet is disclosed. In one embodiment, the photoluminescent sheet includes i) a phosphor, for absorbing some light, of at least one wavelength, of light emitted from a light source and emitting particular light of a wavelength different from the wavelength of the emitted light, ii) a matrix, for having the phosphor, the remaining of the light emitted from the light source penetrating the matrix and iii) a passivation film, for being laminated to at least one surface of the matrix, whereas a roughness is formed on a surface of the passivation film to reduce a contacting area between the photoluminescent sheet and another sheet. According to one embodiment of the present invention, wet is not generated on a screen even though the photoluminescent sheet is connected to other sheets.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described with regard to the accompanying drawings.

FIG. 1 illustrates a typical back light unit (BLU).

FIG. 2 is a sectional diagram illustrating a section of a typical diffusion sheet for wet preventing.

FIG. 3 is a sectional diagram illustrating a section of a first kind of a photoluminescent sheet according to one embodiment of the present invention.

FIG. 4 is a sectional diagram illustrating a section of a second kind of a photoluminescent sheet according to one embodiment of the present invention.

FIG. 5 is a sectional diagram illustrating a section of a third kind of a photoluminescent sheet according to one embodiment of the present invention.

FIG. 6 is a sectional diagram illustrating a section of a photoluminescent sheet in accordance with a first embodiment of the present invention.

FIG. 7 is a sectional diagram illustrating a section of a photoluminescent sheet in accordance with a second embodiment of the present invention.

FIG. 8 is a sectional diagram illustrating a section of a photoluminescent sheet in accordance with a third embodiment of the present invention.

FIG. 9 is a sectional diagram illustrating a section of a photoluminescent sheet in accordance with a fourth embodiment of the present invention.

FIG. 10 is an enlarged diagram illustrating a surface of a photoluminescent sheet having a really embodied wet preventing function in accordance with the first embodiment of the present invention.

Claims

1. A photoluminescent sheet, comprising: a main body containing a phosphor and comprising two opposing surfaces wherein the main body is configured to 1) absorb light, of at least one wavelength, emitted from a light source, 2) emit light of a wavelength different from the wavelength of the emitted light and 3) allow the remaining of the light emitted from the light source to penetrate the photoluminescent sheet; anda passivation film formed on at least one of the two opposing surfaces of the main body, wherein the passivation film has an uneven surface configured to substantially prevent the main body from contacting an adjacent sheet.

2. The photoluminescent sheet of claim 1, wherein the passivation film comprises a plurality of spherically shaped particles which are spatially formed with respect to each other.

3. The photoluminescent sheet of claim 2, wherein the particles are formed of one of a transparent inorganic material and a high molecule resin, and wherein each of the particles has a diameter between about 3 μm and about 30 μm.

4. The photoluminescent sheet of claim 3, wherein the particles are formed of one of silicon dioxide (SiO2) and titanium (IV) oxide (TiO2).

5. The photoluminescent sheet of claim 3, wherein the high molecule resin is one of polymethylmethacrylate (PMMA), polystyrene (PS) and polycarbonate (PC).

6. The photoluminescent sheet of claim 1, wherein the passivation film is formed of a colorless transparent synthetic resin.

7. The photoluminescent sheet of claim 6, wherein the colorless transparent synthetic resin is one of polyethylene terephthalate (PET), polyethylene naphthalene, an acrylic resin, polycarbonate and polystyrene.

8. The photoluminescent sheet of claim 1, wherein the passivation film has a thickness between about 10 μm and 50 μm.

9. The photoluminescent sheet of claim 1, wherein the main body further contains a light diffusing agent.

10. The photoluminescent sheet of claim 9, wherein the light diffusing agent is formed of one of a high molecular compound and an inorganic compound.

11. The photoluminescent sheet of claim 10, wherein the high molecular compound is one of an acrylic resin, an epoxy resin, a styrene resin, a silicon resin, synthetic silica, glass bead and diamond.

12. The photoluminescent sheet of claim 10, wherein the inorganic compound is one of silicon dioxide (SiO2), titanium (IV) oxide (TiO2), zinc oxide (ZnO), barium sulfate (BASO4), calcium sulfate (CaSO4), magnesium carbonate (MgCO3) and aluminum hydroxide (Al(OH)3).

13. The photoluminescent sheet of claim 9, wherein the light diffusing agent comprises a plurality of spherically shaped particles, and wherein each of the particles has a diameter between about 3 μm and 20 μm.

14. The photoluminescent sheet of claim 9, wherein the light diffusing agent has the density of about 1% to 15% with respect to the entire components of the main body.

15. The photoluminescent sheet of claim 1, wherein the phosphor comprises at least one of a yellow phosphor, a red phosphor and a green phosphor.

16. The photoluminescent sheet of claim 15, wherein the yellow phosphor is one of Y3Al5O12 (YAG) and TAG composition (Tb3Al5O12), and silicate composition (Sr2SiO4:Eu).

17. The photoluminescent sheet of claim 15, wherein the red phosphor is one of CaS:Eu, SrS:Eu and SrB4O7:Sm.

18. The photoluminescent sheet of claim 15, wherein the green phosphor is SrGa2S4:Eu.

19. The photoluminescent sheet of claim 1, wherein the phosphor comprises a plurality of particles, and wherein each of the phosphor particles has a size between about 5 μm and 30 μm.

20. The photoluminescent sheet of claim 1, wherein the main body is formed of a thermosetting resin.

21. The photoluminescent sheet of claim 20, wherein the thermosetting resin has the light permeability of about 85 percents or more.

22. A back light unit, comprising: a light source configured to emit light;a photoluminescent sheet containing a plurality of phosphor particles and comprising two opposing surfaces, wherein the photoluminescent sheet is configured to 1) absorb light, of at least one wavelength, emitted from a light source, 2) emit light of a wavelength different from the wavelength of the emitted light and 3) allow the remaining light to pass through the photoluminescent sheet; anda passivation film formed on at least one of the two opposing surfaces of the photoluminescent sheet, wherein the passivation film has an uneven surface which contacts neither of the two opposing surfaces of the photoluminescent sheet,wherein the photoluminescent sheet has a first thickness and the passivation film has a second thickness which is substantially less than the first thickness.

23. The back light unit of claim 22, wherein the passivation film is configured to substantially prevent the photoluminescent sheet from contacting an adjacent sheet.

24. The back light unit of claim 22, wherein the back light unit is incorporated into a liquid crystal display.

25. The back light unit of claim 22, wherein the passivation film comprises a plurality of beads which are spatially formed with respect to each other.