Double-sided lens sheet and projection screen

• US 7,088,508 B2
• Filed: 06/18/2002
• Issued: 08/08/2006
• Est. Priority Date: 06/18/2001
• Status: Expired due to Fees

• Current Assignee: Toppan Printing Co., Ltd. (TOPPAN Holdings, Inc.)
• Original Assignee: Toppan Printing Co., Ltd. (TOPPAN Holdings, Inc.)
• Inventors: Abe, Takashi, Takahashi, Susumu, Miyashita, Masaru, Ebina, Kazuyoshi
• Primary Examiner(s): Perkey, W. B.
• Assistant Examiner(s): Cruz, Magda
• Application Number:
  US10/344,999
• Publication Number:
  US 20030169332A1
• Time in Patent Office: 1,512 Days
• Field of Search: 359455-457, 359/619, 359/449, 359451-452, 359/460
• US Class Current: 359/455
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 3/0068 arranged in a single integral body or plate, e.g. laminates or hybrid structures with other optical elements G02B5/1885, G02B17/002, G02B30/27 take precedence
• CPC Class Codes: G02B 3/06 with cylindrical or toric faces
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

In order to provide a dual-surface lens sheet in which a color shift is reduced and positions of unit lenses on a front surface and a back surface are easily aligned even if the unit lenses are disposed in fine pitch when used for a rear projection screen which is used for a display device using a plurality of projector as light sources, a half-column-cylindrical-convex-lens is used in a lens sheet having lens sections on front surface and a back surface such that pitch ratio for disposing the unit lenses on the front surface and the back surface is in a range of 1:2 to 1:30 and disposition directions of the lens sections are uniform.

Claims

1. A dual-surface lens sheet having periodic gaps contained in lens sections on a front surface and a back surface in a lens sheet wherein pitch ratio of a unit lens on the front surface and the back surface is in a range of 1:

2 to 1;

30, and a shape of each unit lens is a triangle or a hexagon, wherein;

the lens sections on the front surface and the back surface are micro-lens array sections in which the unit lenses are disposed in a matrix manner on a plain surface;

one of the lens sections on the front surface and the back surface is a half-column-cylindrical-convex-lens group and the other lens section is a micro-lens array section in which the unit lenses are disposed utilizing an approximately secondary dimensional matrix;

pitch in which the unit lens in the half-column-cylindrical-convex-lens group is disposed is 0.3 mm or less;

pitch in which the unit lens in the micro-lens array section is disposed is 0.15 mm or less;

a light emission angle emitted from each unit lens is more than ±

30 degrees with respect to a normal of a main surface of the micro-lens array section; and

a ratio of a transverse spherical aberration which is caused by each unit lens is designed to be in a range of 0% to 50% of a diameter of the unit lens.

2. A dual-surface lens sheet according to claim 1, wherein the lens sections on the front surface and the back surface are half-column-cylindrical-convex-lenses which are disposed in uniform disposition direction.

3. A dual lens sheet according to claim 1, wherein the micro-lens array section is made of a reacted product of a radioactive-ray-curable-resin and includes the unit lens having aspherical shape.

4. A dual lens sheet according to claim 1, wherein the micro-lens array section includes only a unit lens having aspherical shape.

5. A dual lens sheet according to claim 1, wherein, in the micro-lens array section, optical diffusion by the lens function in each unit lens is different in a horizontal direction and a vertical direction.

6. A dual lens sheet according to claim 1, wherein periodical gaps are formed for forming the lens section on one surface of the micro-lens sheet, the other surface is flat, and the lens sheets are layered such that the flat surfaces of each sheet are corresponding.

7. A micro-lens sheet according to claim 6, wherein a shading layer is formed in an area corresponding to a non-light-condensing section by each unit lens on a flat surface of at least one of the lens sheets away from the lens section.

8. A dual lens sheet according to claim 1, wherein a unit lens having a convex shape is disposed in the lens section, a focusing surface of at least one of the lens sections exists in the dual lens sheet, and parallel lights which are incident to one of the unit lens pass through a plurality of unit lens in the other lens section when emitted from the lens section in the other lens section.

9. A rear projection screen comprising:

a dual-surface lens sheet having periodic gaps contained in a lens section on a front surface and a back surface in a lens sheet wherein a pitch ratio of a unit lens on the front surface and the back surface is in a range of 1;

2 to 1;

30, and a shape of each unit lens is a triangle or a hexagon; and

a Fresnel lens sheet,

wherein a pitch of a unit lens on a surface of the dual-surface lens sheet is larger than a pitch of a unit lens on an opposite surface of the dual-surface lens sheet;

a lens section in the dual-surface lens sheet having the larger disposition pitch faces a lens section in the Fresnel lens sheet;

the Fresnel lens sheet is disposed nearer a plurality of projectors than the dual-surface lens sheets;

the lens sections on the front surface and the back surface are micro-lens array sections in which the unit lenses are disposed in a matrix manner on a plain surface;

one of the lens sections on the front surface and the back surface is a half-column-cylindrical-convex-lens group and the other lens section is a micro-lens array section in which the unit lenses are disposed utilizing an approximately secondary dimensional matrix, pitch in which the unit lens in the half-column-cylindrical-convex-lens group is disposed is 0.3 mm or less, and pitch in which the unit lens in the micro-array section is disposed is 0.15 mm or less;

a light emission angle emitted from each unit lens is more than ±

30 degrees with respect to a normal of a main surface of the micro-lens array section; and

a ratio of a transverse spherical aberration which is caused by each unit lens is designed to be in a range of 0% to 50% of a diameter of the unit lens.

10. A rear projection screen having a three-tube CRT projector as a light source and a rear projection screen according to claim 9.

11. A micro-lens sheet having a micro-lens array section in which unit lenses are disposed in an approximate matrix in a second dimensional manner on at least one surface of a base board wherein a diameter of each unit lens and a disposition pitch of the unit lenses is 200 μ

m or less, a light emission angle emitted from each unit lens is more than ±

30 degrees with respect to a normal of a main surface of the micro-lens sheet, and a ratio of a transverse spherical aberration which is caused by each unit lens is designed to be in a range of 0% to 50% of a diameter of the lens, and a shape of each unit lens is a triangle or a hexagon.

12. A micro-lens sheet according to claim 11, wherein a shading layer is formed on another surface of the base board which is disposed away from the micro-lens array section such that a light-condensing section by each unit lens becomes an aperture section.

13. A micro-lens sheet according to claim 12, wherein the shading layer is formed so as to have an area which is 75% of an entire area of the micro-lens array section or larger.

14. A micro-lens sheet according to claim 12, wherein the shading layer is formed on a surface of the non-light-condensing section on a photo-sensitive resin layer in which the light-condensing section and the non-light-condensing section are formed according to the light-condensation of the micro-lens array section.

15. A micro-lens sheet according to claim 14, wherein the photo-sensitive resin layer is formed on a surface of the base board, which is separated from the micro-lens array section via a transparent resin layer having a lower refractive index than a refractive index of the base board or the photo-sensitive resin layer, is directly formed on a surface of the base board so as to have the lower refractive index than the refractive index of the base board such that the photo-sensitive resin layer is separated from the micro-lens array section.

16. A rear-projection screen having a size that is 30 inches or larger using the micro-lens sheet according to claim 11.

17. A projection screen according to claim 16, wherein the light-diffusion layer in which a light diffusion member is dispersed is disposed near the Fresnel-lens sheet or the micro-lens sheet.

18. A projection screen according to claim 11, wherein the Fresnel-lens sheet is disposed on the projector as a projection light source.

19. A front-projection screen having a size that is 30 inches or larger, and having the micro-lens sheet according to claim 11, wherein the light-reflection layer is disposed on a surface of the base board which is opposite to the lens.

20. A display device having a backlight and having the micro-lens sheet according to claim 11 as a light-guiding member to control a light emission from the light source under condition of uniform brightness or in a uniform emission direction in a display screen.