Diffuser plate and method for designing diffuser plate

• US 10,551,633 B2
• Filed: 09/30/2015
• Issued: 02/04/2020
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Kuraray Company Limited
• Original Assignee: Kuraray Company Limited
• Inventors: Uchida, Atsushi, Karai, Masaru
• Primary Examiner(s): Collins, Darryl J
• Assistant Examiner(s): Sumlar, Journey F
• Application Number:
  US15/515,426
• Publication Number:
  US 20170235154A1
• Time in Patent Office: 1,588 Days
• CPC Class Codes: G02B 27/0012 Optical design, e.g. procedures, algorithms, optimisation routines
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/0284 used in reflection
• CPC Class Codes: G03B 21/602 Lenticular screens G03B21/625 takes precedence
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

The present invention provides a diffuser plate in a simple structure capable of achieving optical properties with less luminance irregularity and color irregularity and good quality of appearance. A diffuser plate is a diffuser plate where a plurality of microlenses are placed on a principal surface, shapes of the plurality of microlenses along a cross-section perpendicular to the principal surface are different from one another and do not have an axis of symmetry. A method for designing the diffuser plate includes steps of determining a specific reference microlens; placing the reference microlens on the principal surface; forming a specific phase modulation shape; and determining a shape of the plurality of microlenses by combining the specific reference microlens and the specific phase modulation shape.

Claims

1. A diffuser plate where a plurality of microlenses are placed on a principal surface, wherein shapes of the plurality of microlenses along a cross-section perpendicular to the principal surface are different from one another and do not have an axis of symmetry,

wherein

the diffuser plate is a transmissive diffuser plate,

the plurality of microlenses are convex lenses, and

0.2≤

Δ

H×

(n−

1)×

1000/λ

is satisfied where Δ

H [μ

m] is a difference between a maximum height and a minimum height of an apex of a convex surface of the plurality of microlenses from the principal surface, n is a refractive index of the microlens, and λ

[nm] is a wavelength of incidence light.

2. The diffuser plate according to claim 1,

wherein a surface shape of each of the plurality of microlenses along the cross-section consists only of curves without any linear side surfaces, and

wherein a shape of the plurality of microlenses is a composite shape of one reference microlens repetitively placed on the principal surface and a phase modulation shape having a curve continuously varying with respect to the principal surface.

3. A diffuser plate where a plurality of microlenses are placed on a principal surface, wherein shapes of the plurality of microlenses along a cross-section perpendicular to the principal surface are different from one another and do not have an axis of symmetry,

wherein

the diffuser plate is a transmissive diffuser plate,

the plurality of microlenses are concave lenses, and

0.2≤

Δ

D×

(n−

1)×

1000/λ

is satisfied where Δ

D [μ

m] is a difference between a maximum depth and a minimum depth of an apex of a concave surface of the plurality of microlenses from the principal surface, n is a refractive index of the microlens, and λ

[nm] is a wavelength of incidence light.

4. The diffuser plate according to claim 3,

wherein a surface shape of each of the plurality of microlenses along the cross-section consists only of curves without any linear side surfaces, and

wherein a shape of the plurality of microlenses is a composite shape of one reference microlens repetitively placed on the principal surface and a phase modulation shape having a curve continuously varying with respect to the principal surface.