DIFFUSER PLATE AND METHOD FOR PRODUCING DIFFUSER PLATE

• US 20170235028A1
• Filed: 09/29/2015
• Published: 08/17/2017
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Kuraray Company Limited
• Original Assignee: Kuraray Company Limited
• Inventors: HIRAI, Masashi, UCHIDA, Atsushi, KARAI, Masaru
• Granted Patent: US 10,451,778 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 3/00 Simple or compound lenses
• CPC Class Codes: G02B 3/0031 Replication or moulding, e.g. hot embossing, UV-casting, injection moulding
• CPC Class Codes: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/0294 adapted to provide an additional optical effect, e.g. anti-reflection or filter
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001

Abstract

The present invention provides a diffuser plate and a method for producing a diffuser plate that can improve variations in luminance of transmitted light or reflected light in a simple structure and that enable easy design and production. The diffuser plate according to the present invention is a diffuser plate where a plurality of microlenses are placed on a principal surface, wherein a phase difference generation part is inserted between the plurality of microlenses and the principal surface, the plurality of microlenses have two or more types of lens shapes, and the number of microlenses having the two or more types of lens shapes is determined so that a quantity ratio of the two or more types of lens shapes is a specific value, each of the lens shape types is selected corresponding to each of coordinates on the principal surface in which centers of undersurfaces of the plurality of microlenses are placed, and an angle range in which the diffuse light intensity is substantially uniform is in a range of +10% to −10% of a desired angle range.

Claims

1. A diffuser plate, comprising a plurality of microlenses placed on a principal surface, wherein;

a phase difference generation part is inserted between the plurality of microlenses and the principal surface,

the plurality of microlenses have two or more types of lens shapes, and the number of microlenses having the two or more types of lens shapes is determined so that a quantity ratio of the two or more types of lens shapes is a specific value,

each of the lens shape types is selected corresponding to each of coordinates on the principal surface in which centers of undersurfaces of the plurality of microlenses are placed,

when an arithmetic average of diffuse light intensity in a desired angle range in the diffuser plate is 1, a standard deviation of relative intensity of diffuse light intensity in the desired angle range is equal to or less than 9.00×

10<sup>−

2</sup>, and an angle range in which the diffuse light intensity is substantially uniform is in a range of +10% to −

10% of the desired angle range, where the angle range in which the diffuse light intensity is substantially uniform is a difference between a diffusion angle at which an absolute value reaches its maximum on a positive side and a diffusion angle at which an absolute value reaches its minimum on a negative side, out of diffusion angles with a relative intensity of 90% with respect to an arithmetic average of diffuse light intensity in the desired angle range, when a direction along a light incidence direction is at a diffusion angle of 0°

, one direction in an angle distribution measurement direction is positive, and an opposite direction is negative in an angle distribution of diffuse light intensity in one direction of the diffuser plate.

2. The diffuser plate according to claim 1, wherein a maximum value of a phase difference caused by the phase difference generation part is larger than 0.2 times a wavelength of light to be used.

3. The diffuser plate according to claim 1, wherein the desired angle range AngA is 0°

≦

AngA≦

40°

.

4. The diffuser plate according to claim 1, wherein a height of the phase difference generation part from the principal surface varies in accordance with an algebraic function, an elementary function or a composite function of them where coordinates in which the plurality of microlenses are placed are independent variables.

5. The diffuser plate according to claim 1, wherein a height of the phase difference generation part from the principal surface is set randomly.

6. The diffuser plate according to claim 1, wherein a type of the microlens is selected in accordance with an algebraic function, an elementary function or a composite function of them where coordinates in which the microlens is placed are independent variables.

7. The diffuser plate according to claim 1, wherein a type of the microlens is selected randomly for coordinates in which the microlens is placed.

8. A method for producing a diffuser plate where a plurality of microlenses are placed on a principal surface, the method comprising:

designing a plurality of types of microlens sets where the plurality of microlenses are placed on a principal surface, the plurality of microlenses having one type of lens shape with which an angle distribution of diffuse light intensity close to a desired angle range is obtained, and a phase difference generation part is inserted between the plurality of microlenses and the principal surface;

producing a plurality of types of sample molds having shapes respectively corresponding to the plurality of types of microlens sets;

transferring a shape of one type of microlens set to a resin with a sample mold, and thereby producing a plurality of types of sample diffuser plates each having one type of diffusion pattern of the microlens set;

evaluating optical properties of each of the plurality of types of sample diffuser plates;

designing a microlens array combining the plurality of types of microlens sets based on evaluation results of each of the plurality of types of sample diffuser plates;

producing a diffusion pattern mold having a shape corresponding to the microlens array; and

transferring the diffusion pattern to the resin with the diffusion pattern mold.