US3712713A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical shield of transparant intermeshed grooved panels useful on overhead projects
Assignee: 3M Co
•
Filing: 1970-08-10
•
Granted: 1973-01-23
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Expires: 1990-08-10
Abstract
Abstract A glare control shield having particular utility in an overhead projector, consists of fully transparent matching grooved plates which are disposed between stage and Fresnel condensing lens of the projector and with the grooves generally directed toward the position of the operator. Other applications are described.
Inventors
- 👤 R Appledorn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:41
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/04; G02B5/045; G03; G03B; G03B21/00; G03B21/132
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
66 words
An optical shield having parallel smooth outer surfaces and consisting essentially of two fully transparent intermeshing identically longitudinally ridged and grooved panels wherein the adjacent faces of the ridges or grooves are disposed at an included angle of at least about 100* and not greater than about 120* wherein said faces are all disposed at substantially the same angle with respect to the smooth outer surfaces.
Claim 2
Dependent Claim
66 words
An optical shield having parallel smooth outer surfaces and consisting essentially of two fully transparent intermeshing identically longitudinally ridged and grooved panels wherein the adjacent faces of the ridges or grooves are disposed at an included angle of at least about 100* and not greater than about 120* wherein said faces are all disposed at substantially the same angle with respect to the smooth outer surfaces.
Claim 3
Dependent Claim
17 words
The shield of claim 1 wherein said faces are disposed at an included angle of about 110*.
Claim 4
Dependent Claim
23 words
The shield of claim 2 wherein said ridges and grooves are at a uniform constant spacing of not greater than about 2 mils.
Claim 5
Dependent Claim
14 words
The shield of claim 2 wherein said panels are constructed of methyl methacrylate polymer.
Claim 6
Dependent Claim
106 words
An overhead projEctor including a light source, a stage for supporting a transparency containing projection images, a projection head, and a condensing lens for directing light from said source through said stage to said projection head for projection of said images onto a viewing screen, and characterized by the inclusion, in a position between said lens and said stage, of an optical shield consisting essentially of two fully transparent intermeshing longitudinally ridged and grooved panels wherein the adjacent faces of the ridges or grooves are disposed at an included angle of about 110* and with the ridges and grooves directed toward the sides of said projector.
Claim 7
Dependent Claim
106 words
An overhead projEctor including a light source, a stage for supporting a transparency containing projection images, a projection head, and a condensing lens for directing light from said source through said stage to said projection head for projection of said images onto a viewing screen, and characterized by the inclusion, in a position between said lens and said stage, of an optical shield consisting essentially of two fully transparent intermeshing longitudinally ridged and grooved panels wherein the adjacent faces of the ridges or grooves are disposed at an included angle of about 110* and with the ridges and grooves directed toward the sides of said projector.
Claim 8
Dependent Claim
18 words
The overhead projector of claim 5 wherein said condensing lens is included as a component of said shield.
References Cited (Backward Citations)
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Cited
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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) | 1976-01-23 | 1976-07-24 | 1977-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-23 | 1980-07-24 | 1981-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-23 | 1984-07-24 | 1985-01-23 | $7700.00 | Window Closed / Lapsed |