Light diffuser and its use

Patent metadata

Field	Value
Publication number	US-10088609-B2
Application number	US-201415023821-A
Country	US
Kind code	B2
Filing date	Sep 24, 2014
Priority date	Sep 30, 2013
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

There is provided a light diffuser which can alleviate glare of light emitted from a light source while preventing a decrease in brightness of the emitted light despite the presence of the light diffuser. The light diffuser, contains a thermoplastic resin and transparent particles added thereto. The light diffuser has a total light transmittance in a range of 50 to 85%, and a wavelength selectivity in a rectilinear light ratio in a range of 1.5 to 5.0, as obtained by following formulas (1)-(3):

(wavelength selectivity in rectilinear light ratio)=(rectilinear light ratio of 550-nm light)/(rectilinear light ratio of 450-nm light)  (1)

(rectilinear light ratio of 550-nm light)=(rectilinear light transmittance for 550-nm light)/(total transmittance for 550-nm light)  (2)

(rectilinear light ratio of 450-nm light)=(rectilinear light transmittance for 450-nm light)/(total transmittance for 450-nm light)  (3).

First claim

The invention claimed is:

1. A light diffuser which comprises a thermoplastic resin and transparent particles added thereto,
the light diffuser having:
a total light transmittance in a range of 50 to 85%; and
a wavelength selectivity in a rectilinear light ratio in a range of 1.5 to 5.0, as obtained by following formulas (1)-(3):
(wavelength selectivity in rectilinear light ratio)=(rectilinear light ratio of 550-nm light)/(rectilinear light ratio of 450-nm light)   (1)

(rectilinear light ratio of 550-nm light)=(rectilinear light transmittance for 550-nm light)/(total transmittance for 550-nm light)  (2)

(rectilinear light ratio of 450-nm light)=(rectilinear light transmittance for 450-nm light)/(total transmittance for 450-nm light)  (3), and

the thermoplastic resin being a polycarbonate resin or an acrylic resin.

2. The light diffuser according to claim 1 , which is a light diffusion plate having a thickness in a range of 0.5 to 3 mm.

3. The light diffuser according to claim 1 , wherein an amount of the transparent particles is in a range of 0.5 to 2.0% by weight.

4. The light diffuser according to claim 1 , wherein the rectilinear light ratio of 450-nm light obtained by the formula (3) is in a range of 0.01 to 0.5.

5. The light diffuser according to claim 1 , wherein the light diffuser satisfies an inequality:
0.01< D×|np−nm|< 0.1
wherein D is a volume-average particle size (μm) of the transparent particles, np is a refractive index of the transparent particles, and nm is a refractive index of the thermoplastic resin.

6. The light diffuser according to claim 1 , which is used for an LED light source.

7. A laminated light diffuser which comprises the light diffuser according to claim 1 and another light diffuser laminated thereon,
the other light diffuser having:
a total light transmittance in a range of 50 to 90%; and
a degree of dispersion in a range of 5 to 60°, wherein the degree of dispersion is defined as a transmission angle at which a light transmittance is 50% of a rectilinear light transmittance when a surface of the other light diffuser is irradiated from a direction normal to the surface.

8. The laminated light diffuser according to claim 7 , which is used for an LED light source.

9. A light diffusion cover for an LED luminaire which comprises the light diffuser according to claim 6 and which has a cylindrical or part-cylindrical shape.

10. A light diffusion cover for an LED luminaire which comprises the light diffuser according to claim 6 and which has a shape of a light bulb.

11. A light diffusion cover for an LED luminaire which comprises the laminated light diffuser according to claim 8 and which has a cylindrical or part-cylindrical shape.

12. A light diffusion cover for an LED luminaire which comprises the laminated light diffuser according to claim 8 which has a shape of a light bulb.

13. An LED luminaire which comprises the light diffusion cover for an LED luminaire according to claim 9 .

Assignees

• Sekisui Plastics

Inventors

• Ishimori Fumitaka
• Machida Kazuki

Classifications

• G02B5/0242

  by means of dispersed particles · CPC title

• F21K9/232 Primary

  specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb · CPC title

• F21Y2101/00

  Point-like light sources · CPC title

• F21K9/69

  Details of refractors forming part of the light source · CPC title

• G02B5/02 Primary

  Diffusing elements; Afocal elements · CPC title