Projection lens system

Claim 2

A lens system for projecting an image of a concave object surface onto a planar display screen, characterized in that the system lens, comprises first and third elements, each of positive power and each having one aspheric surface, and a second element between first and third elements, said second element having one aspheric surface, the powers of the elements being chosen so that 0.50K<K.sub.1 <0.90K -0.35K<K.sub.2 <0.20K, and 0.70K<K.sub.3 <1.0K where K 1 is the power of the first element remote from the object surface, K 2 is the power of the second element, K 3 is the power of the third element adjacent to the object surface and K is the total power of the projection lens, each aspheric surface being defined by the following relationship: ##EQU3## where Z is a deviation, in the axial direction, of the surface from a plane normal to the optical axis and tangent to the surface at its pole for a zone of the surface which is at a distance s from the axis, C is a curvature of the surface on the axis, ε is a conic constant, and a 4 , a 6 , a 8 and a 10 are constants for the surface.

Claim 3

A lens system as claimed in claim 1, having focal length 13.7 cm at a wavelength of 525 nm, relative aperture f/1.0, projection angle ±26°, throw 1.16 m and magnification 8.26X, and being described substantially as follows: ______________________________________ Polar Axial Axial radius, thickness, separation, Refractive cm cm cm index ______________________________________ L1 S1 9.589 -- -- -- S2 239.00 3.300 -- 1.490 L2 S3 plane -- 3.415 -- S4 -93.982 0.850 -- 1.490 L3 S5 20.031 -- 4.632 -- S6 -12.973 2.996 -- 1.490 FP S7 -13.333 -- 4.775 -- S8 -13.333 1.500 -- 1.520 ______________________________________ Aspheric surfaces: S2, S4, S5 S2 S4 S5 ______________________________________ C 0.00418 .sup. -0.0106 .sup. 0.0499 ε 1 1 l a.sub.4 +0.8870 × 10.sup.-4 +0.2880 × 10.sup.-3 -0.8359 × 10.sup.-4 a.sub.6 -0.1131 × 10.sup.-5 +0.4906 × 10.sup.-5 +0.1480 × 10.sup.-5 a.sub.8 +0.2566 × 10.sup.-8 -0.4938 × 10.sup.-7 -0.1753 × 10.sup.-7 a.sub.10 0 +0.3060 × 10.sup.-8 0 ______________________________________ Element values: Relative Focal length, cm Power, cm.sup.-1 Power ______________________________________ L1 + L2 + L3 13.7 0.073 1 L1 20.29 0.049 0.68 L2 191.8 0.005 0.07 L3 16.56 0.060 0.83 ______________________________________ where L1, L2, L3, FP are successive lens elements from the image end and s1-S8 are successive element surfaces, positive surfaces being convex towards the image end and negative surfaces being concave towards the image end.

Claim 4

A lens system as claimed in claim 1, having focal length 14.2 cm at a wavelength of 525 nm, relative aperture f/0.95, projection angle ±22.62° throw 1.37 m and magnification 9.25X, and being described substantially as follows: ______________________________________ Polar Axial Axial radius, thickness, separation, Refractive cm cm cm index ______________________________________ L1 S1 9.833 -- -- -- S2 115.11 4.280 -- 1.5727 L2 S3 plane -- 1.723 -- S4 31.870 0.500 -- 1.5727 L3 S5 22.369 -- 4.316 -- S6 -13.923 4.012 -- 1.5727 FP S7 -15.625 -- 6.428 -- S8 -16.770 1.200 -- 1.520 ______________________________________ Aspheric surfaces: S2, S4, S5 S2 S4 S5 ______________________________________ C 0.00869 .sup. 0.03138 .sup. 0.0447 ε 1 1 1 a.sub.4 -0.3958 × 10.sup.-4 +0.4186 × 10.sup.-3 -0.3470 × 10.sup.-4 a.sub.6 -0.6202 × 10.sup.-6 +0.3424 × 10.sup.-5 -0.7809 × 10.sup.-6 a.sub.8 +0.7273 × 10.sup.-8 +0.6976 × 10.sup.-7 +0.2470 × 10.sup.-7 a.sub.10 .sup. +0.8549 × 10.sup.-10 +0.2836 × 10.sup.-9 .sup. -0.3791 × 10.sup.-10 ______________________________________ Element values: Relative Focal length, cm Power, cm.sup.-1 Power ______________________________________ L1 + L2 + L3 14.2 0.0703 1 L1 18.500 0.0541 0.77 L2 -55.694 -0.0180 -0.26 L3 15.613 0.0605 0.91 ______________________________________ where L1, L2, L3, EP are successive lens elements from the image end and S1-S8 are successive element surfaces, positive surfaces being convex towards the image end and negative surfaces being concave towards the image end.

Claim 5

A lens system as claimed in claim 1 having focal length 8.93 cm at a wavelength of 525 nm, relative aperture f/1.0, projection angle -37.23° throw 0.75 m and magnification 8X, and being described substantially as follows: ______________________________________ Polar Axial Axial radius, thickness, separation, Refractive cm cm cm index ______________________________________ L1 S1 6.308 -- -- -- S2 23.947 2.273 -- 1.5727 L2 S3 100.837 -- 1.159 -- S4 54.609 0.507 -- 1.5727 L3 S5 17.901 -- 2.301 -- S6 -8.569 2.870 -- 1.5727 FP S7 -10.452 -- 4.174 -- S8 -10.425 1.200 -- 1.520 ______________________________________ Aspheric surfaces: S2, S4, S5 S2 S4 S5 ______________________________________ C 0.0418 .sup. 0.0183 .sup. 0.0559 .sup. ε 1 1 1 a.sub.4 -0.6521 × 10.sup.-4 +0.1338 × 10.sup.-2 -0.2446 × 10.sup.-3 a.sub.6 -0.2200 × 10.sup.-4 +0.4718 × 10.sup.-4 +0.9434 × 10.sup.-5 a.sub.8 +0.4278 × 10.sup.-6 +0.1058 × 10.sup.-5 -0.1444 × 10.sup.-6 a.sub.10 +0.5720 × 10.sup.-8 +0.1786 × 10.sup.-8 -0.4900 × 10.sup.-9 ______________________________________ Element values: Relative Focal length, cm Power, cm.sup.-1 Power ______________________________________ L1 + L2 + L3 8.93 0.112 1 L1 14.285 0.070 0.63 L2 -208.8 -0.0048 -0.04 L3 10.535 0.095 0.85 ______________________________________ where L1, L2, L3, FP are successive lens elements from the image end and S1-S8 are successive element surfaces, positive surfaces being convex towards the image end and negative surfaces being concave towards the image end.

Claim 6

A projection television system comprising a cathode ray tube having a face plate concave towards a lens system, characterized in that the lens system includes first and third lens elements, each of positive power and each having one aspheric surface, and a second lens element disposed between the first and third lens elements, said second lens element having one aspheric surface, the powers of the lens elements being chosen so that 0.50K<K.sub.1 <0.90K -0.35K<K.sub.2 <0.20K, and 0.70K<K.sub.3 <1.0K where K 1 is the power of the first lens element remote from the object surface, K 2 is the power of the second lens element, K 3 is the power of the third lens element adjacent to the object surface and K is the total power of the lens system, each aspheric surface being defined by the following relationship: ##EQU4## where Z is a deviation, in the axial direction, of the surface from a plane normal to the optical axis and tangent to the surface at its pole for a zone of the surface which is at a distance s from the axis, C is a curvature of the surface on the axis, ε is a conic constant, and a 4 , a 6 , a 8 and a 10 are constants for the surface.

Claim 7

A projection television system comprising a cathode ray tube having a face plate concave towards a lens system, characterized in that the lens system includes first and third lens elements, each of positive power and each having one aspheric surface, and a second lens element disposed between the first and third lens elements, said second lens element having one aspheric surface, the powers of the lens elements being chosen so that 0.50K<K.sub.1 <0.90K -0.35K<K.sub.2 <0.20K, and 0.70K<K.sub.3 <1.0K where K 1 is the power of the first lens element remote from the object surface, K 2 is the power of the second lens element, K 3 is the power of the third lens element adjacent to the object surface and K is the total power of the lens system, each aspheric surface being defined by the following relationship: ##EQU4## where Z is a deviation, in the axial direction, of the surface from a plane normal to the optical axis and tangent to the surface at its pole for a zone of the surface which is at a distance s from the axis, C is a curvature of the surface on the axis, ε is a conic constant, and a 4 , a 6 , a 8 and a 10 are constants for the surface.

Claim 8

A color television projection system comprising first, second and third cathode ray tubes having red, blue and green phosphors, respectively, provided on concave face plates, a lens system associated with each cathode ray tube, each lens system being arranged to project an image on the associated concave face plate onto a common display screen, characterized in that each lens system includes first and third lens elements, each of positive power and each having one aspheric surface, and a second lens element between the first and third lens elements, said second lens element having one aspheric surface, the powers of the lens elements being chosen so that 0.50K<K.sub.1 <0.90K -0.35K<K.sub.2 <0.20K, and 0.70K<K.sub.3 <1.0K where K 1 is the power of the first lens element remote from the object surface, K 2 is the power of the second lens element, K 3 is the power of the third lens element adjacent to the object surface and K is the total power of the lens system, each aspheric surface being defined by the following relationship: ##EQU5## where Z is a deviation, in the axial direction, of the surface from a plane normal to the optical axis and tangent to the surface at its pole for a zone of the surface which is at a distance s from the axis, C is a curvature of the surface on the axis, ε is a conic constant, and a 4 , a 6 , a 8 and a 10 are constants for the surface.

Claim 9

A color television projection system comprising first, second and third cathode ray tubes having red, blue and green phosphors, respectively, provided on concave face plates, a lens system associated with each cathode ray tube, each lens system being arranged to project an image on the associated concave face plate onto a common display screen, characterized in that each lens system includes first and third lens elements, each of positive power and each having one aspheric surface, and a second lens element between the first and third lens elements, said second lens element having one aspheric surface, the powers of the lens elements being chosen so that 0.50K<K.sub.1 <0.90K -0.35K<K.sub.2 <0.20K, and 0.70K<K.sub.3 <1.0K where K 1 is the power of the first lens element remote from the object surface, K 2 is the power of the second lens element, K 3 is the power of the third lens element adjacent to the object surface and K is the total power of the lens system, each aspheric surface being defined by the following relationship: ##EQU5## where Z is a deviation, in the axial direction, of the surface from a plane normal to the optical axis and tangent to the surface at its pole for a zone of the surface which is at a distance s from the axis, C is a curvature of the surface on the axis, ε is a conic constant, and a 4 , a 6 , a 8 and a 10 are constants for the surface.