Projection lens for projection television

Claim 2

A projection lens for magnifying an image displayed on a cathode-ray tube and projecting the magnified image on a projection screen, comprising a first lens having a substantially plano surface opposite to said cathode-ray tube and a concave surface, a second lens which is a convex meniscus lens having a concave surface opposite to said concave surface of said first lens, a third convex lens having a strongest refracting power, and a fourth convex lens having a weak refractive power which is spaced apart by a predetermined distance from said third lens, said first to fourth lenses being arranged in the above order, said predetermined distance between said third and fourth lenses being large enough to permit interposition of a plano reflecting mirror therebetween; wherein the radius of surface curvature, clear aperture, axial distance between surfaces, index of refraction and aspherical coefficient have the values shown in the following tables respectively, and the f-number is 0.95: ______________________________________ Distance Surface Clear between Refrac- radius aperture surfaces tion Lens Surface (mm) (mm) (mm) index ______________________________________ First lens S.sub.1 ∞ 127.0 5.0 1.4936 S.sub.2 64.0 90.0 51.0 1.0 Second lens S.sub.3 -100.0 100.0 20.0 1.4936 S.sub.4 -80.8 120.0 1.11 1.0 Third lens S.sub.5 230.0 118.0 32.0 1.4936 S.sub.6 -101.1 116.9 115.0 1.0 Fourth lens S.sub.7 ∞ 130.0 10.0 1.4936 S.sub.8 -242.7 130.0 ______________________________________ where S 1 , S 3 , S 5 , and S 7 indicate the surfaces of the respective lenses on the side of said cathode-ray tube, and S 2 , S 4 , S 6 and S 8 indicate the other surfaces of the respective lenses; ______________________________________ Aspherical Coefficient Surface CC AD AE AF AG ______________________________________ S.sub.2 -0.30 7.57 × 10.sup.-7 1.38 × -1.70 × 1.02 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.3 0 -1.01 × 1.sup.-6 8.43 × -4.95 × 1.17 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.6 0 -1.16 × 10.sup.-7 2.94 × -3.76 × 1.99 × 10.sup.-11 10.sup.-16 10.sup.-19 S.sub.8 -1.96 3.42 × 10.sup.-8 2.68 × -4.74 × 4.01 × 10.sup.-11 10.sup.-15 10.sup.-19 ______________________________________ wherein the aspherical coefficients CC, AD, AE, AF and AG are those included in the following equation which represents the axial displacement Z at a semi-aperture distance r from the optical axis of the lens: ##EQU6## where C is the reciprocal of the radius of curvature at the optical axis.

Claim 3

A projection lens for magnifying an image displayed of a cathode-ray tube and projecting the magnified image on a projection screen, comprising a first lens having a substantially plano surface opposite to said cathode-ray tube and a concave surface, a second lens which is a convex meniscus lens having a concave surface opposite to said concave surface of said first lens, a third convex lens having a strongest positive refracting power, and a fourth convex lens having a weak refractive index which is spaced apart by a predetermined distance from said third lens, said first to fourth lenses being arranged in the above order, said predetermined distance between said third and fourth lenses being large enough to permit interposition of a plano reflecting mirror therebetween; wherein the radius of surface curvature, clear aperture, axial distance between surfaces, index of refraction and aspherical coefficient have the values shown in the following tables respectively, and the f-number is 0.95: ______________________________________ Distance Surface Clear between Refrac- radius aperture surfaces tion Lens Surface (mm) (mm) (mm) index ______________________________________ First lens S.sub.1 ∞ 127.0 5.0 1.4936 S.sub.2 64.0 90.0 51.0 1.0 Second lens S.sub.3 -100.0 100.0 20.0 1.4936 S.sub.4 -80.8 120.0 1.11 1.0 Third lens S.sub.5 230.0 118.0 32.0 1.4936 S.sub.6 -101.1 116.9 115.0 1.0 Fourth lens S.sub.7 ∞ 130.0 10.0 1.4936 S.sub.8 -242.7 130.0 ______________________________________ where S 1 , S 3 , S 5 and S 7 indicate the surfaces of the respective lenses on the side of said cathode-ray tube, and S 2 , S 4 , S 6 and S 8 indicate the other surfaces of the respective lenses, and in the table, the values related to the lens surface S 6 are those measured when an aperture diaphragm is provided; ______________________________________ Aspherical Coefficient Surface CC AD AE AF AG ______________________________________ S.sub.2 -0.30 7.57 × 10.sup.-7 1.38 × -1.70 × 1.02 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.3 0 -1.01 × 1.sup.-6 8.43 × -4.95 × 1.17 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.6 0 -1.16 × 10.sup.-7 2.94 × -3.76 × 1.99 × 10.sup.-11 10.sup.-16 10.sup.-19 S.sub.8 -1.96 3.42 × 10.sup.-8 2.68 × -4.74 × 4.01 × 10.sup.-11 10.sup.-15 10.sup.-19 ______________________________________ wherein the aspherical coefficients CC, AD, AE, AF and AG are those included in the following equation which represents the axial displacement Z at a semi-aperture distance r from the optical axis of the lens: ##EQU7## Where C is the reciprocal of the radius of curvature at the optical axis.

Claim 4

A projection lens for magnifying an image displayed of a cathode-ray tube and projecting the magnified image on a projection screen, comprising a first lens having a substantially plano surface opposite to said cathode-ray tube and a concave surface, a second lens which is a convex meniscus lens having a concave surface opposite to said concave surface of said first lens, a third convex lens having a strongest positive refracting power, and a fourth convex lens having a weak refractive index which is spaced apart by a predetermined distance from said third lens, said first to fourth lenses being arranged in the above order, said predetermined distance between said third and fourth lenses being large enough to permit interposition of a plano reflecting mirror therebetween; wherein the radius of surface curvature, clear aperture, axial distance between surfaces, index of refraction and aspherical coefficient have the values shown in the following tables respectively, and the f-number is 0.95: ______________________________________ Distance Surface Clear between Refrac- radius aperture surfaces tion Lens Surface (mm) (mm) (mm) index ______________________________________ First lens S.sub.1 ∞ 127.0 5.0 1.4936 S.sub.2 64.0 90.0 51.0 1.0 Second lens S.sub.3 -100.0 100.0 20.0 1.4936 S.sub.4 -80.8 120.0 1.11 1.0 Third lens S.sub.5 230.0 118.0 32.0 1.4936 S.sub.6 -101.1 116.9 115.0 1.0 Fourth lens S.sub.7 ∞ 130.0 10.0 1.4936 S.sub.8 -242.7 130.0 ______________________________________ where S 1 , S 3 , S 5 and S 7 indicate the surfaces of the respective lenses on the side of said cathode-ray tube, and S 2 , S 4 , S 6 and S 8 indicate the other surfaces of the respective lenses, and in the table, the values related to the lens surface S 6 are those measured when an aperture diaphragm is provided; ______________________________________ Aspherical Coefficient Surface CC AD AE AF AG ______________________________________ S.sub.2 -0.30 7.57 × 10.sup.-7 1.38 × -1.70 × 1.02 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.3 0 -1.01 × 1.sup.-6 8.43 × -4.95 × 1.17 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.6 0 -1.16 × 10.sup.-7 2.94 × -3.76 × 1.99 × 10.sup.-11 10.sup.-16 10.sup.-19 S.sub.8 -1.96 3.42 × 10.sup.-8 2.68 × -4.74 × 4.01 × 10.sup.-11 10.sup.-15 10.sup.-19 ______________________________________ wherein the aspherical coefficients CC, AD, AE, AF and AG are those included in the following equation which represents the axial displacement Z at a semi-aperture distance r from the optical axis of the lens: ##EQU7## Where C is the reciprocal of the radius of curvature at the optical axis.

Claim 5

A projection lens for magnifying an image displaced on a cathode-ray tube and projecting the magnified image on a projection screen, comprising a first lens having a substantially plano surface opposite to said cathode-ray tube and a concave surface, a second lens which is a convex meniscus lens having a concave surface opposite to said concave surface of said first lens, a third convex lens having a strongest refracting power, and a fourth convex lens having a weak refractive power which is spaced apart by a predetermined distance from said third lens, said first to fourth lenses being arranged in the above order, said predetermined distance between said third and fourth lenses being large enough to permit interposition of a plano reflecting mirror therebetween; wherein said third lens is made of a glass material, and said first lens, said second lens and said fourth lens are made of a synthetic resin material; wherein the lens data have the values shown in the following tables respectively, and the f-number is 0.9: ______________________________________ Distance Surface Clear between Refrac- radius aperture surfaces tion Lens Surface (mm) (mm) (mm) index ______________________________________ First lens S.sub.1 ∞ 127.0 5.0 1.4936 S.sub.2 64.0 90.0 51.0 1.0 Second lens S.sub.3 -100.0 100.0 20.0 1.4936 S.sub.4 -80.8 120.0 1.11 1.0 Third lens S.sub.5 230.0 118.0 32.0 1.4936 S.sub.6 -101.1 116.9 115.0 1.0 Fourth lens S.sub.7 ∞ 130.0 10.0 1.4936 S.sub.8 -242.7 130.0 ______________________________________ where S 1 , S 3 , S 5 and S 7 indicate the surfaces of the respective lenses on the side of said cathode-ray-tube, and S 2 , S 4 , S 6 and S 8 indicate the other surfaces of the respective lenses; ______________________________________ Aspherical Coefficient Surface CC AD AE AF AG ______________________________________ S.sub.2 -0.30 7.57 × 10.sup.-7 1.38 × -1.70 × 1.02 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.3 0 -1.01 × 1.sup.-6 8.43 × -4.95 × 1.17 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.6 0 -1.16 × 10.sup.-7 2.94 × -3.76 × 1.99 × 10.sup.-11 10.sup.-16 10.sup.-19 S.sub.8 -1.96 3.42 × 10.sup.-8 2.68 × -4.74 × 4.01 × 10.sup.-11 10.sup.-15 10.sup.-19 ______________________________________ wherein the aspherical coefficients CC, AD, AE, AF and AG are those included in the following equation which represents the axial displacement Z at the semi-aperture distance r from the optical axis of the lens: ##EQU8## where C is the reciprocal of the radius of curvature at the optical axis.

Claim 6

A projection lens for magnifying an image displaced on a cathode-ray tube and projecting the magnified image on a projection screen, comprising a first lens having a substantially plano surface opposite to said cathode-ray tube and a concave surface, a second lens which is a convex meniscus lens having a concave surface opposite to said concave surface of said first lens, a third convex lens having a strongest refracting power, and a fourth convex lens having a weak refractive power which is spaced apart by a predetermined distance from said third lens, said first to fourth lenses being arranged in the above order, said predetermined distance between said third and fourth lenses being large enough to permit interposition of a plano reflecting mirror therebetween; wherein said third lens is made of a glass material, and said first lens, said second lens and said fourth lens are made of a synthetic resin material; wherein the lens data have the values shown in the following tables respectively, and the f-number is 0.9: ______________________________________ Distance Surface Clear between Refrac- radius aperture surfaces tion Lens Surface (mm) (mm) (mm) index ______________________________________ First lens S.sub.1 ∞ 127.0 5.0 1.4936 S.sub.2 64.0 90.0 51.0 1.0 Second lens S.sub.3 -100.0 100.0 20.0 1.4936 S.sub.4 -80.8 120.0 1.11 1.0 Third lens S.sub.5 230.0 118.0 32.0 1.4936 S.sub.6 -101.1 116.9 115.0 1.0 Fourth lens S.sub.7 ∞ 130.0 10.0 1.4936 S.sub.8 -242.7 130.0 ______________________________________ where S 1 , S 3 , S 5 and S 7 indicate the surfaces of the respective lenses on the side of said cathode-ray-tube, and S 2 , S 4 , S 6 and S 8 indicate the other surfaces of the respective lenses; ______________________________________ Aspherical Coefficient Surface CC AD AE AF AG ______________________________________ S.sub.2 -0.30 7.57 × 10.sup.-7 1.38 × -1.70 × 1.02 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.3 0 -1.01 × 1.sup.-6 8.43 × -4.95 × 1.17 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.6 0 -1.16 × 10.sup.-7 2.94 × -3.76 × 1.99 × 10.sup.-11 10.sup.-16 10.sup.-19 S.sub.8 -1.96 3.42 × 10.sup.-8 2.68 × -4.74 × 4.01 × 10.sup.-11 10.sup.-15 10.sup.-19 ______________________________________ wherein the aspherical coefficients CC, AD, AE, AF and AG are those included in the following equation which represents the axial displacement Z at the semi-aperture distance r from the optical axis of the lens: ##EQU8## where C is the reciprocal of the radius of curvature at the optical axis.

Claim 7

A projection lens for magnifying an image displayed on a cathode-ray tube and projecting the magnified image on a projection screen, comprising a first lens having a substantially plano surface opposite to said cathode-ray tube and a concave surface, a second lens which is a convex meniscus lens having a concave surface opposite to said concave surface of said first lens, a third convex lens having a strongest positive refracting power, and a fourth convex lens having a weak refractive power which is spaced apart by a predetermined distance from said third lens, said first to fourth lenses being arranged in the above order, said predetermined distance between said third and fourth lenses being large enough to permit interposition of a plano reflecting mirror therebetween; wherein said third lens is made of a glass material, and said first lens, said second lens and said fourth lens are made of a synthetic resin material; wherein the lens data have the values shown in the following tables respectively, and the f-number is 0.9: ______________________________________ Distance Surface Clear between Refrac- radius aperture surfaces tion Lens Surface (mm) (mm) (mm) index ______________________________________ First lens S.sub.1 ∞ 127.0 5.0 1.4936 S.sub.2 64.0 90.0 51.0 1.0 Second lens S.sub.3 -100.0 100.0 20.0 1.4936 S.sub.4 -80.8 120.0 1.11 1.0 Third lens S.sub.5 230.0 118.0 32.0 1.4936 S.sub.6 -101.1 116.9 115.0 1.0 Fourth lens S.sub.7 ∞ 130.0 10.0 1.4936 S.sub.8 -242.7 130.0 ______________________________________ where S 1 , S 3 , S 5 and S 7 indicate the surfaces of the respective lenses on the side of said cathode-ray tube, and S 2 , S 4 , S 6 and S 8 indicate the other surfaces of the respective lenses; ______________________________________ Aspherical Coefficient Surface CC AD AE AF AG ______________________________________ S.sub.2 -0.30 7.57 × 10.sup.-7 1.38 × -1.70 × 1.02 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.3 0 -1.01 × 1.sup.-6 8.43 × -4.95 × 1.17 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.6 0 -1.16 × 10.sup.-7 2.94 × -3.76 × 1.99 × 10.sup.-11 10.sup.-16 10.sup.-19 S.sub.8 -1.96 3.42 × 10.sup.-8 2.68 × -4.74 × 4.01 × 10.sup.-11 10.sup.-15 10.sup.-19 ______________________________________ wherein thee aspherical coefficients CC, AD, AE, AF and AG are those included in the following equation which represents the axial displacement Z at a semi-aperture distance r from the optical axis of the lens: ##EQU9## where C is the reciprocal of the radius of curvature at the optical axis.

Claim 8

A projection lens for magnifying an image displayed on a cathode-ray tube and projecting the magnified image on a projection screen, comprising a first lens having a substantially plano surface opposite to said cathode-ray tube and a concave surface, a second lens which is a convex meniscus lens having a concave surface opposite to said concave surface of said first lens, a third convex lens having a strongest positive refracting power, and a fourth convex lens having a weak refractive power which is spaced apart by a predetermined distance from said third lens, said first to fourth lenses being arranged in the above order, said predetermined distance between said third and fourth lenses being large enough to permit interposition of a plano reflecting mirror therebetween; wherein said third lens is made of a glass material, and said first lens, said second lens and said fourth lens are made of a synthetic resin material; wherein the lens data have the values shown in the following tables respectively, and the f-number is 0.9: ______________________________________ Distance Surface Clear between Refrac- radius aperture surfaces tion Lens Surface (mm) (mm) (mm) index ______________________________________ First lens S.sub.1 ∞ 127.0 5.0 1.4936 S.sub.2 64.0 90.0 51.0 1.0 Second lens S.sub.3 -100.0 100.0 20.0 1.4936 S.sub.4 -80.8 120.0 1.11 1.0 Third lens S.sub.5 230.0 118.0 32.0 1.4936 S.sub.6 -101.1 116.9 115.0 1.0 Fourth lens S.sub.7 ∞ 130.0 10.0 1.4936 S.sub.8 -242.7 130.0 ______________________________________ where S 1 , S 3 , S 5 and S 7 indicate the surfaces of the respective lenses on the side of said cathode-ray tube, and S 2 , S 4 , S 6 and S 8 indicate the other surfaces of the respective lenses; ______________________________________ Aspherical Coefficient Surface CC AD AE AF AG ______________________________________ S.sub.2 -0.30 7.57 × 10.sup.-7 1.38 × -1.70 × 1.02 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.3 0 -1.01 × 1.sup.-6 8.43 × -4.95 × 1.17 × 10.sup.-10 10.sup.-13 10.sup.-16 S.sub.6 0 -1.16 × 10.sup.-7 2.94 × -3.76 × 1.99 × 10.sup.-11 10.sup.-16 10.sup.-19 S.sub.8 -1.96 3.42 × 10.sup.-8 2.68 × -4.74 × 4.01 × 10.sup.-11 10.sup.-15 10.sup.-19 ______________________________________ wherein thee aspherical coefficients CC, AD, AE, AF and AG are those included in the following equation which represents the axial displacement Z at a semi-aperture distance r from the optical axis of the lens: ##EQU9## where C is the reciprocal of the radius of curvature at the optical axis.