Screen, fresnel lens sheet used for the same, and image display apparatus using the same

• US 7,697,202 B2
• Filed: 04/15/2008
• Issued: 04/13/2010
• Est. Priority Date: 02/09/2004
• Status: Expired due to Fees

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yoshikawa, Hiroki, Hirata, Koji, Ohishi, Tetsu, Imafuku, Daisuke
• Primary Examiner(s): Epps; Georgia Y
• Assistant Examiner(s): Cruz; Magda
• Application Number:
  US12/103,241
• Publication Number:
  US 20080204868A1
• Time in Patent Office: 728 Days
• Field of Search: 359/457, 359/456, 359/460, 359/443, 359/459, 359/454, 359/831, 359833-834, 359/837
• US Class Current: 359/457
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

An image display apparatus includes an image generation source, optics for projecting in an enlarged form the image generated by the image generation source, and a transmissive screen for displaying the image projected from said optics. The transmissive screen includes a Fresnel lens sheet disposed at an image generation source side, and a diffusing sheet disposed at an image-watching side in order to diffuse image light at least in a horizontal direction of the screen. The Fresnel lens sheet has a plurality of entrance-side prisms formed at the image generation source side, and a plurality of exit-side prisms formed at the image-watching side, and the Fresnel lens sheet emits lights in a first direction and a second direction. The first direction is almost parallel to a central axis of the Fresnel lens sheet, and the second direction extends toward the central axis.

Claims

1. An image display apparatus comprising:

an image generation source;

optics for projecting in an enlarged form an image generated by said image generation source; and

a transmissive screen for displaying the image projected from said optics;

wherein said transmissive screen includes at least both a Fresnel lens sheet disposed at an image generation source side, and a diffusing sheet disposed at an image-watching side, the diffusing sheet diffusing image light in at least a horizontal direction of said screen;

the Fresnel lens sheet includes both a totally reflective prism formed at the image generation source side, and a refractive prism formed at the image-watching side, the totally reflective prism not only being formed in a region where the light enters at an angle equal to or greater than a desired incident angle, at the image generation source side of the Fresnel lens sheet, but also including both an entrance face from which the light enters, and a totally reflective face that reflects the incident light entering from the entrance face and makes the light exit toward the image-watching side; and

the totally reflective face is constructed of more than at least two faces, or as a spherical face or a nonspherical face, for causing the incident light from the entrance face to go out as exit rays of exit angles with more than at least two directions.

2. The image display apparatus according to claim 1, wherein the region where said refractive prism is provided is such a region that causes the rays exiting from said totally reflective prism to overlap more than at least one pitch of said refractive prism.

3. The image display apparatus according to claim 1, wherein;

on a transparent base material constituting said Fresnel lens sheet, said totally reflective prism and said refractive prism are formed using ultraviolet-cured resin; and

a transmittance of a first ultraviolet-cured resin layer for forming said totally reflective prism is lower than a transmittance of a second ultraviolet-cured resin layer for forming said refractive prism.

4. The image display apparatus according to claim 1, wherein:

on a transparent base material constituting said Fresnel lens sheet, said totally reflective prism and said refractive prism are formed using ultraviolet-cured resin; and

a diffusing material is contained in the ultraviolet-cured resin used to form said refractive prism, and/or in the ultraviolet-cured resin used to form said totally reflective prism.