Light-scattering light-guiding device

• US 5,548,670 A
• Filed: 07/25/1994
• Issued: 08/20/1996
• Est. Priority Date: 11/27/1992
• Status: Expired due to Term

• Current Assignee: Yasuhiro Koike
• Original Assignee: Yasuhiro Koike
• Inventors: Koike, Yasuhiro
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): Palmer, Phan T. H.
• Application Number:
  US08/256,775
• Time in Patent Office: 757 Days
• Field of Search: 385/27, 385/31, 385/39, 385/42, 385/15, 385/28, 385/29, 385/30, 385/34, 385/124, 385/146
• US Class Current: 385/27
• CPC Class Codes: G02B 5/0236 the diffusion taking place within the volume of the element
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A light-scattering light-guiding device includes a light-scattering light guide having an incident surface, an exit surface from which scattered light is emitted, and a volume region having uniform scattering power. The volume region has an effective scattering illumination parameter E (cm^-1) whose value satisfies the relation 0.45≦E≦100. The light guide has a nonuniform refractive index structure having a correlation function γ (r), which is approximated by exp {-R/A}, where r is the distance between two points in the light guide. This distance a satisfies the relation 0.01 μm≦a≦50 μm. It is not necessary to form a scattering layer of diffusive ink or the like on the rear surface of the light guide. If an exit direction-modifying device having a prismatic cross section is disposed on the side of the exit surface, the flux of the outgoing light directed in a specified direction can be increased. The nonuniform refractive index structure is obtained by kneading together a polymer matrix and a particulate material of a different refractive index, by kneading together two or more kinds of polymers of different refractive indices, or by dispersing a particulate material, utilizing suspension polymerization. The light guide is obtained by a molding process.

Claims

1. A light-scattering light-guiding device comprising:

a plate-shaped light-scattering light guide having at least one side surface region for receiving light, a light exit surface for emitting outgoing light in an oblique direction, and a volume region having a substantially uniform scattering power,

said volume region having an effective scattering illumination parameter E whose value lies in a range of 0.45 cm^-1 ≦

E≦

100 cm^-1, and a nonuniform refractive index structure for producing said scattering power, said nonuniform refractive index structure being expressed by a correlation function γ

(r) approximated by exp (-r/a), where r is a distance between two points in said volume region and a is a correlation distance whose value lies in a range of 0.01 μ

m≦

a≦

50 μ

m, and

said nonuniform refractive index structure being particulate material uniformly dispersed in a matrix, the refractive index of said particulate material being different from the refractive index of the matrix 0.001 or more.

2. A light scattering light-guiding device according to claim 1, wherein outgoing light emitted from the light exit surface is emitted at a direction of 30°

-40°

with respect to the direction light travels when received by the at least one side surface region.-

3. A light-scattering light-guiding device comprising;

a plate shaped light-scattering light guide having at least one side surface region for receiving light, a light exit surface for emitting outgoing light in a first direction, and a volume region having a substantially uniform scattering power,

said volume region having an effective scattering illumination parameter E whose value lies in a range of 0.45 cm^-1 ≦

E≦

100 cm^-1, and a nonuniform refractive index structure for producing said scattering power, said nonuniform refractive index structure being expressed by a correlation function γ

(r) approximated by exp (-R/a), where r is a distance between two points in said volume region and a is a correlation distance whose value lies in a range of 0.01 μ

m≦

a≦

50 μ

m, and

said nonuniform refractive index structure being particulate material uniformly dispersed in a matrix, the refractive index of said particulate material being different from the refractive index of the matrix by 0.001 or more; and

a light exit direction modifying prismatic element disposed along the light exit surface for changing the direction of the emitted light from the

3. first direction to a second direction. 4. A light scattering light guiding device according to claim 3, wherein the second direction is perpendicular to the light exit surface.