Photoluminescent sheet

Abstract

A photoluminescent sheet is disclosed. In one embodiment, the photoluminescent sheet has a phosphor, absorbs some light, of at least one wavelength, of light emitted from a light source, emits particular light of a wavelength different from the wavelength of the emitted light and allows the remaining of the light emitted from the light source to penetrates the photoluminescent sheet, whereas the photoluminescent sheet comprises at least a surface comprising a wet preventing layer for minimizing a contracting area between the photoluminescent sheet and another sheet. According to at least one embodiment, 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 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 having a wet preventing function in accordance with a first embodiment of the present invention.

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

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

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

FIG. 10 is a sectional diagram illustrating a section of a photoluminescent sheet having a wet preventing function in accordance with a fifth embodiment of the present invention.

FIG. 11 is a sectional diagram illustrating a section of a photoluminescent sheet having a wet preventing function in accordance with a sixth embodiment of the present invention.

FIG. 12 is a sectional diagram illustrating a section of a photoluminescent sheet having a wet preventing function in accordance with a seventh 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 wet preventing layer, formed on at least one of the two opposing surfaces of the main body, configured to minimize a contact area between the main body and another sheet.

2. The photoluminescent sheet of claim 1, wherein the wet preventing layer comprises an uneven surface.

3. The photoluminescent sheet of claim 2, wherein the uneven surface has a sawtooth wave shape.

4. The photoluminescent sheet of claim 1, wherein the wet preventing layer comprises a plurality of spherically shaped particles which are spatially formed with respect to each other.

5. The photoluminescent sheet of claim 4, wherein each of the particles has a diameter between about 3 μm and about 30 μm.

6. The photoluminescent sheet of claim 4, wherein the particles are formed of a transparent inorganic material or a high molecule resin.

7. The photoluminescent sheet of claim 4, wherein the particles are formed of one of the following: polymethylmethacrylate (PMMA), polystyrene (PS), polycarbornate (PC), silicon dioxide (SiO2) and titanium (IV) oxide (TiO2).

8. The photoluminescent sheet of claim 4, wherein the particles are formed of one of the following: a plastic resin, a polyester resin, an acrylic resin, an epoxy resin and a silicon resin.

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

10. The photoluminescent sheet of claim 9, wherein the light diffusing agent is formed of one of the following: a high molecular compound, an inorganic compound, an acrylic resin, an epoxy resin, a styrene resin and a silicon resin, synthetic silica, glass bead and diamond, 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).

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

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

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

14. The photoluminescent sheet of claim 13, wherein the yellow phosphor is one of the following: Y3Al5O12 (YAG) and TAG composition (Tb3Al5O12), and silicate composition (Sr2SiO4:Eu).

15. The photoluminescent sheet of claim 13, wherein the red phosphor is one of CaS:Eu, SrS:Eu and SrB4O7:Sm.

16. The photoluminescent sheet of claim 13, wherein the green phosphor is SrGa2S4:Eu.

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

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

19. The photoluminescent sheet of claim 18, wherein the silicon resin has the light permeability of about 85 percents or more and the viscosity of about 3000 cps or more and is hardened at the temperature of about 150° C. or less.

20. The photoluminescent sheet of claim 1, wherein the photoluminescent sheet is connected to a light guide sheet, configured to guide the light emitted from the light source in a direction.

21. A back light unit, comprising: a light source configured to emit light; anda photoluminescent sheet including a main body and a layer, wherein the main body contains a plurality of phosphor particles and comprising two opposing surfaces, wherein the main body is configured to 1) absorb light, of at least one wavelength, emitted from the 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, wherein the layer is formed on at least one of the two opposing surfaces of the main body, and comprises an uneven surface which contacts neither of the two opposing surfaces of the main body, and wherein the main body has a first thickness and the layer has a second thickness which is substantially less than the first thickness.

22. The back light unit of claim 21, wherein the layer is configured to substantially prevent the main body from contacting an adjacent sheet.

23. The back light unit of claim 21, wherein the back light unit is incorporated into a liquid crystal display.

24. The back light unit of claim 21, wherein the layer comprises a plurality of beads which are spatially formed with respect to each other.

25. The back light unit of claim 21, wherein the uneven surface has a sawtooth wave shape.