Patent US5208620A successfully refreshed from Google Patents.
US5208620A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Display apparatus
Assignee: Canon Inc
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Filing: 1991-06-24
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Granted: 1993-05-04
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Expires: 2011-06-24
Abstract
Abstract A display apparatus comprises a projecting device for projecting an image, with the projecting device having a projection optical system having a limited pupil diameter and screen device arranged at a position where an image is substantially projected by the projecting device. The screen device has at least two sheets in each of which a number of prisms extending like a straight line or a curve are formed on the surface on the side opposite to the projecting device. Each of the prisms has an effective portion for allowing a light flux from the projecting device to be emitted in a predetermined direction and a non-effective portion which does not contribute to the emission of the light flux in the predetermined direction, and wherein the non-effective portions of another one or a plurality of the other sheets among the plurality of sheets excluding the sheet arranged at the nearest position on the projecting device side are formed so as to have an almost intermediate angle between the angle of a principal ray when a light flux from the projecting device progresses in the sheets and the emission angle of the principal ray when it is emitted from effective surfaces of the prisms of the sheets.
Inventors
- 👤 Hideaki Mitsutake
- 👤 Nobuo Minoura
- 👤 Katsumi Kurematsu
- 👤 Haruyuki Yanagi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:28
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/74; H04N5/7408; G; G03; G03B; G03B21/00; G03B21/10
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
198 words
A display apparatus comprising: projecting means for projecting an image, said projecting means having a projection optical system having a limited pupil diameter; and screen means arranged at a position where an image is substantially projected by said projecting means, said screen means having a plurality of Fresnel lens sheets each having a number of prisms formed on a surface on a side opposite to said projecting means, and each of said prisms having an effective portion for allowing a light flux from said projecting means to be emitted in a predetermined direction and a non-effective portion which does not contribute to the emission of the light flux in said predetermined direction, and wherein the non-effective portions of at least one selected sheet from said plurality of Fresnel lens sheets, excluding said sheet arranged at a position nearest to said projecting means, extend in a middle direction substantially between a direction in which a principal ray of a light flux from said projecting means is incident on the effective portions of said prisms of said selected sheet and a direction in which the principal ray is emitted from the effective portions of said prisms of said selected sheet.
Claim 2
Dependent Claim
198 words
A display apparatus comprising: projecting means for projecting an image, said projecting means having a projection optical system having a limited pupil diameter; and screen means arranged at a position where an image is substantially projected by said projecting means, said screen means having a plurality of Fresnel lens sheets each having a number of prisms formed on a surface on a side opposite to said projecting means, and each of said prisms having an effective portion for allowing a light flux from said projecting means to be emitted in a predetermined direction and a non-effective portion which does not contribute to the emission of the light flux in said predetermined direction, and wherein the non-effective portions of at least one selected sheet from said plurality of Fresnel lens sheets, excluding said sheet arranged at a position nearest to said projecting means, extend in a middle direction substantially between a direction in which a principal ray of a light flux from said projecting means is incident on the effective portions of said prisms of said selected sheet and a direction in which the principal ray is emitted from the effective portions of said prisms of said selected sheet.
Claim 3
Dependent Claim
27 words
An apparatus according to claim 1, wherein said screen means has a sheet having a light diffusing function disposed on a side farthest from said projecting means.
Claim 4
Dependent Claim
197 words
A display apparatus comprising: a plurality of projecting means for projecting images, each of said projecting means having a projection optical system having a limited pupil diameter; and screen means arranged at a position where an image is substantially projected by said projecting means, said screen means having a plurality of Fresnel lens sheets each having a number of prisms formed on a surface on a side opposite to said projecting means, each of said prisms having an effective portion to emit a light flux from said projecting means in a predetermined direction and a non-effective portion which does not contribute to the emission of the light flux to said predetermined direction, wherein the non-effective portions of at least one of said plurality of Fresnel lens sheets, excluding said sheet arranged at a position nearest to said projecting means, is formed so as to have a substantially middle angle between the average value of the angles of principal rays when light fluxes from said plurality of projecting means progress in said sheets and the average value of emission angles of the principal rays when they are emitted from the effective portions of said prisms of said sheets.
Claim 5
Dependent Claim
197 words
A display apparatus comprising: a plurality of projecting means for projecting images, each of said projecting means having a projection optical system having a limited pupil diameter; and screen means arranged at a position where an image is substantially projected by said projecting means, said screen means having a plurality of Fresnel lens sheets each having a number of prisms formed on a surface on a side opposite to said projecting means, each of said prisms having an effective portion to emit a light flux from said projecting means in a predetermined direction and a non-effective portion which does not contribute to the emission of the light flux to said predetermined direction, wherein the non-effective portions of at least one of said plurality of Fresnel lens sheets, excluding said sheet arranged at a position nearest to said projecting means, is formed so as to have a substantially middle angle between the average value of the angles of principal rays when light fluxes from said plurality of projecting means progress in said sheets and the average value of emission angles of the principal rays when they are emitted from the effective portions of said prisms of said sheets.
Claim 6
Dependent Claim
27 words
An apparatus according to claim 3, wherein said screen means has a sheet having a light diffusing function disposed on a farthest side from said projecting means.
Claim 7
Independent Claim
217 words
An apparatus for displaying a picture, comprising: projecting optical means for projecting an image; and a screen on which the image is projected, said screen including a first translucent sheet and a second translucent sheet, and wherein a beam for producing the image is transmitted to said second translucent sheet through said first translucent sheet, with said first translucent sheet having a first surface receiving the beam and a second surface on which a first Fresnel lens comprising a plurality of prism-shaped structures is formed, said second translucent sheet having a third surface facing said second surface and a fourth surface receiving the beam through said third surface, and wherein a second Fresnel lens comprising a plurality of prism-shaped structures is formed on said fourth surface, each of said prism-shaped structures of said second Fresnel lens having a refractive surface refracting the beam and another surface, and wherein an angle of said another surface with respect to an axis normal to said second translucent sheet is set so as to have a substantially middle value between an angle of a principal ray with respect to said axis when said beam is incident on said refractive surface and an angle of said principal ray with respect to said axis when said beam is emitted from said refractive surface.
Claim 8
Independent Claim
217 words
An apparatus for displaying a picture, comprising: projecting optical means for projecting an image; and a screen on which the image is projected, said screen including a first translucent sheet and a second translucent sheet, and wherein a beam for producing the image is transmitted to said second translucent sheet through said first translucent sheet, with said first translucent sheet having a first surface receiving the beam and a second surface on which a first Fresnel lens comprising a plurality of prism-shaped structures is formed, said second translucent sheet having a third surface facing said second surface and a fourth surface receiving the beam through said third surface, and wherein a second Fresnel lens comprising a plurality of prism-shaped structures is formed on said fourth surface, each of said prism-shaped structures of said second Fresnel lens having a refractive surface refracting the beam and another surface, and wherein an angle of said another surface with respect to an axis normal to said second translucent sheet is set so as to have a substantially middle value between an angle of a principal ray with respect to said axis when said beam is incident on said refractive surface and an angle of said principal ray with respect to said axis when said beam is emitted from said refractive surface.
Claim 9
Dependent Claim
31 words
An apparatus according to claim 5, wherein said projecting optical means has an optical axis which is inclined to an axis normal to said first surface of said first translucent sheet.
Claim 10
Dependent Claim
27 words
An apparatus according to claim 5, wherein said first surface of said first translucent sheet and said third surface of said second translucent sheet are flat surfaces.
Claim 11
Dependent Claim
63 words
An apparatus according to claim 5, wherein said screen includes a third translucent sheet on the side of said fourth surface of said second translucent sheet, said third translucent sheet having a fifth surface facing said fourth surface and a sixth surface receiving the beam through said fifth surface, and wherein said third translucent sheet has a lenticular lens on said fifth surface.
Claim 12
Dependent Claim
19 words
An apparatus according to claim 8, wherein said sixth surface of said third translucent sheet has a lenticular lens.
Claim 13
Dependent Claim
65 words
An apparatus according to claim 5, wherein said screen includes a third translucent sheet on the side of said fourth surface of said second translucent sheet, said third translucent sheet having a fifth surface facing said fourth surface and a sixth surface on the side opposed to said second translucent sheet, and wherein said third translucent sheet has a lenticular lens on said sixth surface.
Claim 14
Dependent Claim
71 words
An apparatus according to claim 5, wherein said screen includes a third translucent sheet on the side of said fourth surface of said second translucent sheet, said third translucent sheet having a fifth surface facing said fourth surface of said second translucent sheet and a sixth surface on the side opposed to said second translucent sheet, and wherein said third translucent sheet has a Fresnel lens formed on said sixth surface.
Claim 15
Dependent Claim
191 words
A display apparatus, comprising: projecting optical means for projecting an image; and a screen on which the image is projected, said screen including a first translucent sheet and a second translucent sheet, with said first translucent sheet having a first surface and a second surface, with a first Fresnel lens comprising a plurality of prism-shaped structures formed on said second surface, said second translucent sheet having a third surface and a fourth surface, with a second Fresnel lens comprising a plurality of prism-shaped structures formed on said fourth surface, each of said prism-shaped structures of at least one of said first and second Fresnel lenses having a refractive surface refracting a beam indicative of the image and another surface, and wherein an angle of said another surface with respect to an axis normal to said translucent sheets is set so as to have a substantially middle value between an angle of a principal ray with respect to the normal axis when the beam is incident on said refractive surface and an angle of said principal ray with respect to the normal axis when the beam is emitted from said refractive surface.
Claim 16
Dependent Claim
191 words
A display apparatus, comprising: projecting optical means for projecting an image; and a screen on which the image is projected, said screen including a first translucent sheet and a second translucent sheet, with said first translucent sheet having a first surface and a second surface, with a first Fresnel lens comprising a plurality of prism-shaped structures formed on said second surface, said second translucent sheet having a third surface and a fourth surface, with a second Fresnel lens comprising a plurality of prism-shaped structures formed on said fourth surface, each of said prism-shaped structures of at least one of said first and second Fresnel lenses having a refractive surface refracting a beam indicative of the image and another surface, and wherein an angle of said another surface with respect to an axis normal to said translucent sheets is set so as to have a substantially middle value between an angle of a principal ray with respect to the normal axis when the beam is incident on said refractive surface and an angle of said principal ray with respect to the normal axis when the beam is emitted from said refractive surface.
Claim 17
Dependent Claim
178 words
A screen on which an image is projected, comprising: a first translucent sheet; and a second translucent sheet; wherein said first translucent sheet has a first surface and a second surface, with a first Fresnel lens comprising a plurality of prism-shaped structures formed on said second surface, and said second translucent sheet has a third surface and a fourth surface, with a second Fresnel lens comprising a plurality of prism-shaped structures formed on said fourth surface, and each of said prism-shaped structures of at least one of said first and second Fresnel lenses has a refractive surface refracting a beam indicative of the image and another surface, and an angle of said another surface with respect to an axis normal to said translucent sheets is set so as to have a substantially middle value between an angle of a principal ray with respect to the normal axis when the beam is incident on said refractive surface and an angle of said principal ray with respect to the normal axis when the beam is emitted from said refractive surface.
Claim 18
Dependent Claim
178 words
A screen on which an image is projected, comprising: a first translucent sheet; and a second translucent sheet; wherein said first translucent sheet has a first surface and a second surface, with a first Fresnel lens comprising a plurality of prism-shaped structures formed on said second surface, and said second translucent sheet has a third surface and a fourth surface, with a second Fresnel lens comprising a plurality of prism-shaped structures formed on said fourth surface, and each of said prism-shaped structures of at least one of said first and second Fresnel lenses has a refractive surface refracting a beam indicative of the image and another surface, and an angle of said another surface with respect to an axis normal to said translucent sheets is set so as to have a substantially middle value between an angle of a principal ray with respect to the normal axis when the beam is incident on said refractive surface and an angle of said principal ray with respect to the normal axis when the beam is emitted from said refractive surface.
Claim 19
Dependent Claim
196 words
A screen on which an image is projected, comprising: a first translucent sheet; and a second translucent sheet; wherein a beam indicative of the image is transmitted to said second translucent sheet through said first translucent sheet, with said first translucent sheet having a first surface receiving the beam and a second surface on which a first Fresnel lens comprising a plurality of prism-shaped structures is formed, and said second translucent sheet having a third surface facing said second surface and a fourth surface receiving the beam through said third surface and having a second Fresnel lens comprising a plurality of prism-shaped structures formed thereon, and each of said prism-shaped structures of said second Fresnel lens has a refractive surface refracting the beam and another surface, and an angle of said another surface with respect to an axis normal to said translucent sheets is set so as to have a substantially middle value between an angle of a principal ray with respect to the normal axis when the beam is incident on said refractive surface and an angle of said principal ray with respect to said axis when said beam is emitted from said refractive surface.
Claim 20
Dependent Claim
196 words
A screen on which an image is projected, comprising: a first translucent sheet; and a second translucent sheet; wherein a beam indicative of the image is transmitted to said second translucent sheet through said first translucent sheet, with said first translucent sheet having a first surface receiving the beam and a second surface on which a first Fresnel lens comprising a plurality of prism-shaped structures is formed, and said second translucent sheet having a third surface facing said second surface and a fourth surface receiving the beam through said third surface and having a second Fresnel lens comprising a plurality of prism-shaped structures formed thereon, and each of said prism-shaped structures of said second Fresnel lens has a refractive surface refracting the beam and another surface, and an angle of said another surface with respect to an axis normal to said translucent sheets is set so as to have a substantially middle value between an angle of a principal ray with respect to the normal axis when the beam is incident on said refractive surface and an angle of said principal ray with respect to said axis when said beam is emitted from said refractive surface.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-05-03 | 1996-11-02 | 1997-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-05-03 | 2000-11-02 | 2001-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-05-03 | 2004-11-02 | 2005-05-04 | $7700.00 | Window Closed / Lapsed |