Light diffusing body and a transmission type screen

• US 7,320,823 B2
• Filed: 02/12/2007
• Issued: 01/22/2008
• Est. Priority Date: 02/14/2006
• Status: Active Grant

• Current Assignee: Kimoto Company Limited
• Original Assignee: Kimoto Company Limited
• Inventors: Etori, Hideki, Kimura, Yoshihisa, Kitahara, Keiichi
• Primary Examiner(s): Chen; Vivian
• Application Number:
  US11/704,998
• Publication Number:
  US 20070190291A1
• Time in Patent Office: 344 Days
• Field of Search: None
• US Class Current: 428/212
• CPC Class Codes: B32B 2255/10 on synthetic resin layer or on natural or synthetic rubber layer
• CPC Class Codes: B32B 2264/0214 Particles made of materials belonging to B32B27/00
• CPC Class Codes: B32B 2264/0228 Vinyl resin particles, e.g. polyvinyl acetate, polyvinyl alcohol polymers or ethylene-vinyl acetate copolymers
• CPC Class Codes: B32B 2264/0235 Aromatic vinyl resin, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 2264/0292 Polyurethane particles
• CPC Class Codes: B32B 2264/10 Inorganic particles
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2307/414 Translucent
• CPC Class Codes: B32B 2307/518 bi-axially
• CPC Class Codes: B32B 25/08 of synthetic resin
• CPC Class Codes: B32B 25/20 comprising silicone rubber
• CPC Class Codes: B32B 27/00 Layered products comprising a layer of synthetic resin fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 27/40 comprising polyurethanes
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C08L 2205/18 Spheres
• CPC Class Codes: C08L 25/06 Polystyrene
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 33/06 : of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
• CPC Class Codes: G03B 21/62 : Translucent screens
• CPC Class Codes: Y10T 428/24488 : Differential nonuniformity at margin
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Abstract

A light diffusing body and transmission type screen, which can reduce the shift of the color tone of the light source light seen through the light diffusing body and prevent the phenomenon that the white light source seen through the light diffusing body looks colored, is provide.

The light diffusing body 1 of the present invention comprises a transparent resin and spherical micro-particles having a different refractive index from that of the said transparent resin, wherein the relation between the maximum value (E_max) and the minimum value (E_max) of the effective scattering efficiency values (E) obtained for each center wavelength in the wavelength ranges of blue, green and red by dividing the sum of scattering cross-sections of all spherical micro-particles contained in the unit area of the aforementioned light diffusing body 1 by the sum of geometrical cross-sections of all these spherical micro-particles satisfies E_min/E_max≧0.90.

Claims

1. A light diffusing body comprising a transparent resin and spherical micro-particles having a refractive index which is different from that of the transparent resin,

wherein when the value obtained by dividing the sum of scattering cross-sections of all spherical micro-particles contained in the unit area of the light diffusing body by the sum of geometrical cross-sections of all these spherical micro-particles for each of multiple wavelengths, the minimum value of all of values obtained for each wavelength is 90% or higher of the maximum value.

2. The light diffusing body according to claim 1,

wherein the value E obtained by dividing the sum of scattering cross-sections of all spherical micro-particles by the sum of geometrical cross-sections of all these spherical micro-particles is expressed by the following equation (1).

E=∫

₀^maxQ(λ

,r)f(r)dr/∫

₀^maxπ

r²f(r)dr 

 

(1)

(In equation (1), Q is a scattering cross-section of one spherical micro-particle and a function of wavelength λ and

particle diameter r, and f(r) is a particle diameter distribution function.)

3. The light diffusing body according to claim 1,

wherein the multiple wavelengths are center wavelengths in the range of wavelength of blue, green and red.

4. The light diffusing body according to claim 1,

wherein if the refractive index of the transparent resin is n_m and the refractive index of the spherical micro-particles is n_s, n_s/n_m satisfies 0.91<

(n_s/n_m)<

1.09 (however, n_s/n_m≠

1).

5. The light diffusing body according to claim 1,

wherein the surface of the light diffusing body is substantially smooth.

7. A transmission type screen having a light diffusing body according to claim 1.

8. A transmission type screen having a light diffusing layer on one of the surfaces of a transparent substrate, wherein the light diffusing layer uses a light diffusing body according to claim 1.

9. A transmission type screen having a light diffusing layer on one of the surfaces of a transparent substrate, wherein the light diffusing layer uses a light diffusing body according to claim 2.

10. A transmission type screen having a light diffusing layer on one of the surfaces of a transparent substrate, wherein the light diffusing layer uses a light diffusing body according to claim 3.

11. A transmission type screen having a light diffusing layer on one of the surfaces of a transparent substrate, wherein the light diffusing layer uses a light diffusing body according to claim 4.

12. A transmission type screen having a light diffusing layer on one of the surfaces of a transparent substrate, wherein the light diffusing layer uses a light diffusing body according to claim 5.

14. A transmission type screen having a light diffusing body according to claim 2.

15. A transmission type screen having a light diffusing body according to claim 3.

16. A transmission type screen having a light diffusing body according to claim 4.

17. A transmission type screen having a light diffusing body according to claim 5.

6. A light diffusing body having a light diffusing layer and a transparent polymer film laminated on at least one surface of the light diffusing layer,

wherein the light diffusing layer comprises transparent resin and spherical micro-particles having a refractive index different from that of the transparent resin, and

when the value obtained by dividing the sum of scattering cross-sections of all spherical micro-particles contained in the unit area of the light diffusing body by the sum of geometrical cross-sections of all these spherical micro-particles for each of multiple wavelengths, the minimum value of all of values obtained for each wavelength is 90% or higher of the maximum value.

13. A transmission type screen having a light diffusing layer on one of the surfaces of a transparent substrate, wherein the light diffusing layer uses a light diffusing body according to claim 6.

18. A transmission type screen having a light diffusing body according to claim 6.