US4895429A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rear projection apparatus
Assignee: Hitachi Ltd
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Filing: 1988-09-28
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Granted: 1990-01-23
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Expires: 2008-09-28
Abstract
Abstract A rear projection apparatus is disclosed which is provided with at least two optical projection lens units. Two or more projected images are joined to form a single projected image on a screen. A light reflection preventing member is provided on a blocking plate for preventing the adjacent images from overlapping with each other. The reflection preventing member is used for preventing the light, projected onto the blocking plate, from being introduced into the screen, thereby preventing a degradation of contrast.
Inventors
- 👤 Yoshiaki Iwahara
- 👤 Masanori Oguino
- 👤 Yuzo Tamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:39
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/54; G03B21/56; G03B21/60; G03B21/62
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
89 words
A rear projection apparatus having means for joining and projecting at least two images as a single image on a screen, and at least two optical projection means, said rear projection apparatus comprising means for preventing reflection, said reflection preventing means being provided on a surface of a blocking plate for preventing an overlap of the adjacent images on said screen, and said reflection preventing means eliminating a projection of reflected light derived from a ray of light projected on said blocking plate, thus preventing a degradation in contrast.
Claim 2
Dependent Claim
89 words
A rear projection apparatus having means for joining and projecting at least two images as a single image on a screen, and at least two optical projection means, said rear projection apparatus comprising means for preventing reflection, said reflection preventing means being provided on a surface of a blocking plate for preventing an overlap of the adjacent images on said screen, and said reflection preventing means eliminating a projection of reflected light derived from a ray of light projected on said blocking plate, thus preventing a degradation in contrast.
Claim 3
Dependent Claim
53 words
The rear projection apparatus according to claim 1, wherein said reflection preventing means includes sawteeth formed on a surface of said blocking plate, wherein surfaces of said sawteeth are formed at an angle such that the light reflected by said surfaces of said sawteeth is not introduced into the surface of said screen.
Claim 4
Dependent Claim
28 words
The rear projection apparatus according to claim 2, wherein said blocking plate is fixed to an angle mounted between screen components and is used for reinforcing the screen.
Claim 5
Dependent Claim
37 words
The rear projection apparatus according to claim 1, wherein said blocking plate is provided on a frame commonly provided between adjacent screen components, whereby a distance between the adjacent images are made narrow as much as possible.
Claim 6
Dependent Claim
57 words
The rear projection apparatus according to claim 4, wherein a frame part of the blocking plate provided on said frame is made of transparent material, whereby the light is not blocked by the frame part but is passed through said frame part so that a invisible part of the image between the adjacent screen components is reduced.
Claim 7
Dependent Claim
32 words
The rear projection apparatus according to any one of claims 1 to 5, wherein said blocking plate is provided between the screen components or on a continuous screen member between the images.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-22 | 1993-07-24 | 1994-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-22 | 1997-07-24 | 1998-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-22 | 2001-07-24 | 2002-01-23 | $7700.00 | Window Closed / Lapsed |