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US4398810A
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Fresnel lens system
Assignee: B OPTICAL 2915 ANVIL ST N ST PETERSBURG FL 33710 A PARTNERSHIP CONSISTING OF MARVIN P HODGES AD LARRY BAYNARD
•
Filing: 1982-02-18
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Granted: 1983-08-16
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Expires: 2002-02-18
Abstract
Abstract A projection lens system of the type used in connection with cathode ray tubes, and more specifically a cathode ray tube projection system having an internal lens folding means, useful in projecting an image or series of images on a screen.
Inventors
- 👤 Marvin P. Hodges
- 👤 Richard A. Buchroeder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:06
CPC Classifications
G; G02; G02B; G02B3/00; G02B3/02; G02B3/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
171 words
A Fresnel lens system having design parameters normalized for a 280 mm focal length represented by the following table: ______________________________________
Ele- Sepa-
ment R D E F ration
______________________________________
A -364.848 +0.779 ×
-0.1990 ×
+0.2300 ×
mm 10.sup.-8 mm.sup.-3
10.sup.-12 mm.sup.-5
10.sup.-17 mm.sup.-7
280.6mm
(nominal)
B -269.834 +0.3539 ×
-0.118 ×
+0.5003 ×
mm 10.sup.-7 mm.sup.-3
10.sup.-11 mm.sup.-5
10.sup.-16 mm.sup.-7
119.8mm
(nominal)
C -142.473 +0.1322 ×
-0.6375 ×
+0.4502 ×
mm 10.sup.-7 mm.sup.-3
10.sup.-5 mm.sup.-5
10.sup.-17 mm.sup.-7
______________________________________ wherein letters A through C identify the respective lens elements from the screen side to the cathode ray tube side and R, D, E, and F are constants of the following generating function: x=y.sup.2 /2R+Dy.sup.4 +Ey.sup.6 +Fy.sup.8 where y is the zonal ray distance from the optical axis, and wherein and the slope of the generating function given as a tangent, is defined as: tan θ=y/R+4Dy.sup.3 +6Ey.sup.5 +8Fy.sup.7 with all dimensions being expressed in millimeters, and wherein the design parameters may be normalized to any other focal length, lengths and lens materials.
Claim 2
Dependent Claim
171 words
A Fresnel lens system having design parameters normalized for a 280 mm focal length represented by the following table: ______________________________________
Ele- Sepa-
ment R D E F ration
______________________________________
A -364.848 +0.779 ×
-0.1990 ×
+0.2300 ×
mm 10.sup.-8 mm.sup.-3
10.sup.-12 mm.sup.-5
10.sup.-17 mm.sup.-7
280.6mm
(nominal)
B -269.834 +0.3539 ×
-0.118 ×
+0.5003 ×
mm 10.sup.-7 mm.sup.-3
10.sup.-11 mm.sup.-5
10.sup.-16 mm.sup.-7
119.8mm
(nominal)
C -142.473 +0.1322 ×
-0.6375 ×
+0.4502 ×
mm 10.sup.-7 mm.sup.-3
10.sup.-5 mm.sup.-5
10.sup.-17 mm.sup.-7
______________________________________ wherein letters A through C identify the respective lens elements from the screen side to the cathode ray tube side and R, D, E, and F are constants of the following generating function: x=y.sup.2 /2R+Dy.sup.4 +Ey.sup.6 +Fy.sup.8 where y is the zonal ray distance from the optical axis, and wherein and the slope of the generating function given as a tangent, is defined as: tan θ=y/R+4Dy.sup.3 +6Ey.sup.5 +8Fy.sup.7 with all dimensions being expressed in millimeters, and wherein the design parameters may be normalized to any other focal length, lengths and lens materials.
Claim 3
Dependent Claim
35 words
A Fresnel lens system as recited in claim 1 wherein said lens system is designed to protect an image from a convex image plane having a spherical curve of approximately 23 to 25 inches radius.
Claim 4
Dependent Claim
22 words
A Fresnel lens system as recited in claim 2 wherein said image plane is the face plate of a cathode ray tube.
Claim 5
Dependent Claim
21 words
A Fresnel lens system as recited in claim 3 wherein the cathode ray tube has approximately a 13 inch diagonal measure.
Claim 6
Dependent Claim
38 words
A Fresnel lens system as recited in claim 2 wherein the radius of Element A is approximately 171 mm, the radius of Element B is approximately 110 mm, and the radius of Element C is approximately 171 mm.
Claim 7
Dependent Claim
21 words
A Fresnel lens system as recited in claim 5 further including an aperture stop interposed between Element A and Element B.
Claim 8
Dependent Claim
29 words
A Fresnel lens system as recited in claim 6 wherein said aperture stop has a diameter of approximately 152 millimeters and is spaced approximately 204 millimeters from Element A.
Claim 9
Dependent Claim
21 words
A Fresnel lens system as recited in claim 2 further including a folding mirror disposed between Element A and Element B.
Claim 10
Dependent Claim
35 words
A Fresnel lens system as recited in claim 8 wherein said folding mirror is spaced approximately 153 millimeters from Element A and disposed at approximately a 45 degree angle with respect to the optical axis.
Claim 11
Dependent Claim
18 words
A Fresnel lens system as recited in claim 9 wherein said folding mirror operates as an aperture stop.
Claim 12
Dependent Claim
22 words
A Fresnel lens system as recited in claim 9 wherein said convex image plane is tilted with respect to the optical axis.
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) | 1986-08-15 | 1987-02-14 | 1987-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-15 | 1991-02-14 | 1991-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-15 | 1995-02-14 | 1995-08-16 | $7700.00 | Window Closed / Lapsed |