Nova Patents
EP0902316A2

Lenticular lens sheet for rear projection screen

Abstract

A lenticular lens sheet for use as a rear-projection screen, comprises a body sheet; back lenses having a substantially elliptic cross section and formed in a back surface of the body sheet; front lenses formed in a front surface of the body sheet at the focal points of the back lenses or in the vicinity thereof; and a light absorbing layer formed on sections of the front surface at the non-focal points of the back lenses. Pitches p of the back and the front lenses, and thickness t of the lenticular lens sheet equal to distance between a plane in contact with the back lenses and a plane in contact with the front lenses meet an inequality: 1.1 ≦ t/p ≦ 1.4, and conic coefficient k of a conic section defining the cross section of the back lenses is in the range of -0.5 to -0.4.

EP0902316A2, drawing sheet 1
Sheet 1 of 34

Term

Term ended

Projected expiry passed 26 August 2018, 8.1 years ago.

  1. Priority
  2. Filed
  3. Published
  4. Projected expiry
  5. Today

6 claims: 5 independent, 1 dependent

  1. 1
    A lenticular lens sheet (1) for use as a rear-projection screen, comprising:a body sheet having a front surface and a back surface;back lenses (2) having a substantially elliptical cross section and formed in the back surface of the body sheet, said back lenses (2) having focal points, respectively;front lenses (3) formed in the front surface of the body sheet at the focal points of the back lenses (2), or in the vicinity thereof;and a light absorbing layer (4) formed on sections of the front surface at the non-focal points of the back lenses (2);wherein the light absorbing layer (4) is formed in a BS ratio meeting an inequality: BS ≦ (1 - 2w/p) × 100 (%) where: w = ( t - t D /2)tan{sin -1 (sinβ F / n )}+ t D /2×tan{sin -1 (sinβ F / n )+sin -1 (sinβ L / n )} t is a thickness of the lenticular lens sheet (1), t D is a thickness of the diffusing layer, n is a refractive index of the lenticular lens sheet, β F is a 1/3-luminance angle of diffusion of light rays before falling on the lenticular lens sheet (1), and β L is a 1/3-luminance angle of diffusion of light rays caused by the light diffusing material contained in the lenticular lens sheet (1).
  2. 2
    A lenticular lens sheet (1) for use as a rear-projection screen comprising:a body sheet having a front surface and a back surface;back lenses (2) having a substantially elliptical cross section and formed in the back surface of the body sheet, said back lenses (2) having focal points, respectively;front lenses (3) formed in the front surface of the body sheet at the focal points of the back lenses (2), or in the vicinity thereof;and a light absorbing layer (4) formed on sections of the front surface at the non-focal points of the back lenses (2);wherein pitches p of the back (2) and the front (3) lenses, and paraxial radius of curvature c of the back lenses (2) meet an inequality: p/2c ≧ 0.9 , and the conic coefficient k of a conic section defining the cross section of the back lenses (2) is in the range of -0.5 to -0.4.
  3. 4
    The lenticular lens sheet (1) according to one or more of the preceding claims, wherein elevated sections (5) of a substantially rectangular cross section are formed on the front surface at the non-focal points of the back lenses (2), the light absorbing layer (4) is formed on the surfaces of the elevated sections (5), and the pitch p of the back (2) and the front (3) lenses, the BS ratio (%) and height H of the elevated sections (5) from a plane including the tops of the front lenses (3) meet:p(100 - BS)/200H ≧ √3 .
  4. 5
    The lenticular lens sheet (1) according to one or more of the preceding claims, wherein the light absorbing layer (4) is formed on the surfaces of the elevated sections (5), and the ridges of the elevated sections (5) are rounded.
  5. 6
    The lenticular lens sheet (1) according to one or more of the preceding claims, wherein a positional difference d of a point on the front lens (3) from which light rays leaves the lenticular lens sheet (1) from the optical axis of the corresponding front lens (3) meet a condition expressed by:d = p 2 〈 tan[φ-sin -1 { sin(φ-θ) n }]-tan[φ-sin -1 { sin(φ+θ) n }]〉 ÷〈 tan[φ-sin -1 { sin(φ-θ) n }]+tan[φ-sin -1 { sin(φ+θ) n }]〉 where p is the pitch of the back lenses (2), n is the refractive index of the lenticular lens sheet, (1) φ is the angle of a tangent to the back lens (2) at the root edges (2') of the same to a plane including the opposite root edges (2') of each back lens (2), and θ is the angle of the path of a light ray falling on the back lens (2) to the optical axis of the same.
Independent claims5