Projection lens

Claim 2

A projection lens for a projector which projects an image on a screen, said projection lens consisting essentially of, in succession from the screen side, a first lens of a positive refractive power; a second lens of a positive refractive power having a biconvex shape; a third lens of a negative refractive power having a concave surface facing to the screen side and being of the meniscus type; and a fourth lens of a negative refractive power having a concave surface facing to the screen side.

Claim 3

A projection lens according to claim 1, wherein said projection lens satisfies the following condition: -3.0≦P.sub.1 /P.sub.3 ≦-0.8 where P 1 and P 3 are the refractive powers of said first and third lenses.

Claim 4

A projection lens according to claim 1, wherein said projection lens satisfies the following condition: |r.sub.4 |>|r.sub.5 | where r 4 is the radius of curvature of the CRT side lens surface of said second lens, and r 5 is the radius of curvature of the screen side lens surface of said third lens.

Claim 5

A projection lens according to claim 1, wherein said first, third and fourth lenses are formed of plastics whereas said second lens is formed of glass.

Claim 6

A projection lens according to claim 4, wherein said first, third and fourth lenses have non-spherical surfaces and said second lens is a spherical lens.

Claim 7

A projection lens according to claim 5, wherein the air-distance between said second and third lenses is smaller than the center thickness of said third lens.

Claim 8

A projection lens according to claim 6, as represented by the following data: ______________________________________ f = 101.2 Aperture ratio: 1:1.10 Magnification of projection: -7.997.sup.x Half angle of view: 28.56° r.sub.1 = 143.454 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -1542.254 d.sub.2 = 68 r.sub.3 = 116.976 d.sub.3 = 20.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = 110.914 d.sub.4 = 2.87 r.sub.5 = -89.375 d.sub.5 = 5.0 n.sub.3 = 1.59501 L.sub.3 r.sub.6 = -127.071 d.sub.6 = 58.8 r.sub.7 = -48.609 d.sub.7 = 5 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 = 8 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0 C.sub.2 = 0 C.sub.2 = 0 C.sub.4 = -0.25396 × 10.sup.-6 C.sub.4 = -0.15389 × 10.sup.-8 C.sub.4 = -0.16950 × 10.sup.-5 C.sub.6 = +0.22757 × 10.sup.-12 C.sub.6 = -0.25521 × 10.sup.-10 C.sub.6 = -0.40698 × 10.sup.-9 C.sub.8 = -0.21205 × 10.sup.-14 C.sub.8 = +0.92353 × 10.sup.-14 C.sub.8 = +0.31136 × 10.sup.-12 C.sub.10 = -0.90440 × 10.sup.-18 C.sub.10 = -0.60222 × 10.sup.-17 C.sub.10 = -0.46400 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 266.4 f.sub.2 = 94.6 f.sub.3 = -532.7 f.sub.4 = -98.438 where, r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 );

Claim 9

n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surfaces; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 10

n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surfaces; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 11

A projection lens according to claim 6 as represented by the following data: ______________________________________ f = 103.9 Aperture ratio: 1:1.11 Magnification of projection: -7.932.sup.x Half angle of view: 27.1° r.sub.1 = 223.029 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -491.036 d.sub.2 = 90.0 r.sub.3 = 93.718 d.sub.3 = 24.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = -110.115 d.sub.4 = 3.0 r.sub.5 = -87.097 d.sub.5 = 5.0 n.sub.3 = 1.59501 L.sub.3 r.sub.6 = -144.756 d.sub.6 = 56.0 r.sub.7 = -48.366 d.sub.7 = 5.0 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5.0 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 = 8.0 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0 C.sub.2 = 0 C.sub.2 = 0 C.sub.4 = -0.14167 × 10.sup.-6 C.sub.4 = +0.16171 × 10.sup.-6 C.sub.4 = -0.22800 × 10.sup.-5 C.sub.6 = -0.22352 × 10.sup.-10 C.sub.6 = -0.17475 × 10.sup.-9 C.sub.6 = +0.19485 × 10.sup.-9 C.sub.8 = +0.97419 × 10.sup.-14 C.sub.8 = +0.59843 × 10.sup.-13 C.sub.8 = -0.65121 × 10.sup.-13 C.sub.10 = -0.19587 × 10.sup.-17 C.sub.10 = -0.13108 × 10.sup.-16 C.sub.10 = + 0.12473 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 312.2 f.sub.2 = 85.1 f.sub.3 = -379.8 f.sub.4 = -97.9 where r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surface; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 12

A projection lens according to claim 6 as represented by the following data: ______________________________________ f = 103.5 Aperture ratio: 1:1.12 Magnification of projection: -7.952.sup.x Half angle of view: 28.4° r.sub.1 = 258.591 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -383.684 d.sub.2 = 90.0 r.sub.3 = 97.238 d.sub.3 = 22.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = -114.795 d.sub.4 = 3.0 r.sub.5 = -88.542 d.sub.5 = 5.0 n.sub.3 = 1.59048 L.sub.3 r.sub.6 = -130.879 d.sub.6 = 57.5 r.sub.7 = -49.159 d.sub.7 = 5.0 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5.0 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 =0 8.0 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0.0 C.sub.2 = 0.0 C.sub.2 = 0.0 C.sub.4 = -0.15691 × 10.sup.-6 C.sub.4 = +0.95381 × 10.sup.-7 C.sub.4 = -0.22891 × 10.sup.-5 C.sub.6 = -0.40068 × 10.sup.-10 C.sub.6 = -0.73871 × 10.sup.-10 C.sub.6 = +0.12283 × 10.sup.-9 C.sub.8 = +0.21016 × 10.sup.-13 C.sub.8 = +0.12280 × 10.sup.-13 C.sub.8 = +0.84230 × 10.sup.-13 C.sub.10 = -0.37685 × 10.sup.-17 C.sub.10 = -0.33177 × 10.sup.-17 C.sub.10 = - 0.20592 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 314.6 f.sub.2 = 88.0 f.sub.3 = -481.2 f.sub.4 = -99.6 where, r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surface; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 13

A projection lens for a video projector which projects an image of a CRT on a screen, said projection lens comprising, in succession from the screen side, a first lens of a positive refractive power; a second lens of a positive refractive power having a biconvex shape; a third lens of a negative refractive power having a concave surface facing to the screen side; and a fourth lens of a negative refractive power having a concave surface facing to the screen side, further said projection lens being adapted to fulfill the following condition: -3.0≦P.sub.1 /P.sub.3 ≦-0.8 where P 1 and P 3 are the refractive powers of said first and third lenses.

Claim 14

A projection lens for a video projector which projects an image of a CRT on a screen, said projection lens comprising, in succession from the screen side, a first lens of a positive refractive power; a second lens of a positive refractive power having a biconvex shape; a third lens of a negative refractive power having a concave surface facing to the screen side; and a fourth lens of a negative refractive power having a concave surface facing to the screen side, further said projection lens being adapted to fulfill the following condition: -3.0≦P.sub.1 /P.sub.3 ≦-0.8 where P 1 and P 3 are the refractive powers of said first and third lenses.

Claim 15

A projection lens according to claim 10, wherein said third lens is of meniscus type.

Claim 16

A projection lens according to claim 10, wherein said first, third and fourth lenses are formed of plastics whereas said second lens is formed of glass.

Claim 17

A projection lens according to claim 12, wherein said first, third and fourth lenses have non-spherical surfaces and said second lens is a spherical lens.

Claim 18

A projection lens according to claim 13, wherein the air-distance between said second and third lenses is smaller than the center thickness of said third lens.

Claim 19

A projection lens according to claim 14 as represented by the following data: ______________________________________ f = 101.2 Aperture ratio: 1:1.10 Magnification of projection: -7.997.sup.x Half angle of view: 28.56° r.sub.1 = 143.454 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -1542.254 d.sub.2 = 68 r.sub.3 = 116.976 d.sub.3 = 20.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = 110.914 d.sub.4 = 2.87 r.sub.5 = -89.375 d.sub.5 = 5.0 n.sub.3 = 1.59501 L.sub.3 r.sub.6 = -127.071 d.sub.6 = 58.8 r.sub.7 = -48.609 d.sub.7 = 5 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 = 8 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0 C.sub.2 = 0 C.sub.2 = 0 C.sub.4 = -0.25396 × 10.sup.-6 C.sub.4 = -0.15389 × 10.sup.-8 C.sub.4 = -0.16950 × 10.sup.-5 C.sub.6 = +0.22757 × 10.sup.-12 C.sub.6 = -0.25521 × 10.sup.-10 C.sub.6 = -0.40698 × 10.sup.-9 C.sub.8 = -0.21205 × 10.sup.-14 C.sub.8 = +0.92353 × 10.sup.-14 C.sub.8 = +0.31136 × 10.sup.-12 C.sub.10 = -0.90440 × 10.sup.-18 C.sub.10 = -0.60222 × 10.sup.-17 C.sub.10 = -0.46400 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 266.4 f.sub.2 = 94.6 f.sub.3 = -532.7 f.sub.4 = -98.438 where, r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surfaces; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 20

A projection lens according to claim 14 as represented by the following data: ______________________________________ f = 103.9 Aperture ratio: 1:1.11 Magnification of projection: -7.932.sup.x Half angle of view: 27.1° r.sub.1 = 223.029 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -491.036 d.sub.2 = 90.0 r.sub.3 = 93.718 d.sub.3 = 24.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = -110.115 d.sub.4 = 3.0 r.sub.5 = -87.097 d.sub.5 = 5.0 n.sub.3 = 1.59501 L.sub.3 r.sub.6 = -144.756 d.sub.6 = 56.0 r.sub.7 = -48.366 d.sub.7 = 5.0 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5.0 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 = 8.0 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0 C.sub.2 = 0 C.sub.2 = 0 C.sub.4 = -0.14167 × 10.sup.-6 C.sub.4 = +0.16171 × 10.sup.-6 C.sub.4 = -0.22800 × 10.sup.-5 C.sub.6 = -0.22352 × 10.sup.-10 C.sub.6 = -0.17475 × 10.sup.-9 C.sub.6 = +0.19485 × 10.sup.-9 C.sub.8 = +0.97419 × 10.sup.-14 C.sub.8 = +0.59843 × 10.sup.-13 C.sub.8 = -0.65121 × 10.sup.-13 C.sub.10 = -0.19587 × 10.sup.-17 C.sub.10 = -0.13108 × 10.sup.-16 C.sub.10 = + 0.12473 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 312.2 f.sub.2 = 85.1 f.sub.3 = -379.8 f.sub.4 = -97.9 where r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surface; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 21

A projection lens according to claim 14, as represented by the following data: ______________________________________ f = 103.5 Aperture ratio: 1:1.12 Magnification of projection: -7.952.sup.x Half angle of view: 28.4° r.sub.1 = 258.591 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -383.684 d.sub.2 = 90.0 r.sub.3 = 97.238 d.sub.3 = 22.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = -114.795 d.sub.4 = 3.0 r.sub.5 = -88.542 d.sub.5 = 5.0 n.sub.3 = 1.59048 L.sub.3 r.sub.6 = -130.879 d.sub.6 = 57.5 r.sub.7 = -49.159 d.sub.7 = 5.0 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5.0 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 =0 8.0 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0.0 C.sub.2 = 0.0 C.sub.2 = 0.0 C.sub.4 = -0.15691 × 10.sup.-6 C.sub.4 = +0.95381 × 10.sup.-7 C.sub.4 = -0.22891 × 10.sup.-5 C.sub.6 = -0.40068 × 10.sup.-10 C.sub.6 = -0.73871 × 10.sup.-10 C.sub.6 = +0.12283 × 10.sup.-9 C.sub.8 = +0.21016 × 10.sup.-13 C.sub.8 = +0.12280 × 10.sup.-13 C.sub.8 = +0.84230 × 10.sup.-13 C.sub.10 = -0.37685 × 10.sup.-17 C.sub.10 = -0.33177 × 10.sup.-17 C.sub.10 = - 0.20592 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 314.6 f.sub.2 = 88.0 f.sub.3 = -481.2 f.sub.4 = -99.6 where, r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the totl system; C is apex curvature; K is a circular cone constant of the non-spherical surface; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 22

A projection lens for a video projector which projects an image of a CRT on a screen, said projection lens comprising, in succession from the screen side, a first lens of a positive refractive power; a second lens of a positive refractive power having a biconvex shape; a third lens of a negative refractive power having a concave surface facing to the screen side; and a fourth lens of a negative refractive power having a concave surface facing to the screen side, further said projection lens being adapted to fulfill the following condition: |r.sub.4 |>|r.sub.5 | where r 4 is the radius of curvatuve of the CRT side lens surface of said second lens, and r 5 is the radius of curvature of the screen side lens surface of said third lens.

Claim 23

A projection lens for a video projector which projects an image of a CRT on a screen, said projection lens comprising, in succession from the screen side, a first lens of a positive refractive power; a second lens of a positive refractive power having a biconvex shape; a third lens of a negative refractive power having a concave surface facing to the screen side; and a fourth lens of a negative refractive power having a concave surface facing to the screen side, further said projection lens being adapted to fulfill the following condition: |r.sub.4 |>|r.sub.5 | where r 4 is the radius of curvatuve of the CRT side lens surface of said second lens, and r 5 is the radius of curvature of the screen side lens surface of said third lens.

Claim 24

A projection lens according to claim 18, wherein said third lens is of meniscus type.

Claim 25

A projection lens according to claim 18, wherein said first, third and fourth lenses are formed of plastics whereas said second lens is formed of glass.

Claim 26

A projection lens according to claim 20, wherein said first, third and fourth lenses have non-spherical surfaces and said second lens is a spherical lens.

Claim 27

A projection lens according to claim 21, wherein the air-distance between said second and third lenses is smaller than the center thickness of said third lens.

Claim 28

A projection lens according to claim 22 as represented by the following data: ______________________________________ f = 101.2 Aperture ratio: 1:1.10 Magnification of projection: -7.997.sup.x Half angle of view: 28.56° r.sub.1 = 143.454 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -1542.254 d.sub.2 = 68 r.sub.3 = 116.976 d.sub.3 = 20.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = 110.914 d.sub.4 = 2.87 r.sub.5 = -89.375 d.sub.5 = 5.0 n.sub.3 = 1.59501 L.sub.3 r.sub.6 = -127.071 d.sub.6 = 58.8 r.sub.7 = -48.609 d.sub.7 = 5 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 = 8 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0 C.sub.2 = 0 C.sub.2 = 0 C.sub.4 = -0.25396 × 10.sup.-6 C.sub.4 = -0.15389 × 10.sup.-8 C.sub.4 = -0.16950 × 10.sup.-5 C.sub.6 = +0.22757 × 10.sup.-12 C.sub.6 = -0.25521 × 10.sup.-10 C.sub.6 = -0.40698 × 10.sup.-9 C.sub.8 = -0.21205 × 10.sup.-14 C.sub.8 = +0.92353 × 10.sup.-14 C.sub.8 = +0.31136 × 10.sup.-12 C.sub.10 = -0.90440 × 10.sup.-18 C.sub.10 = -0.60222 × 10.sup.-17 C.sub.10 = -0.46400 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 266.4 f.sub.2 = 94.6 f.sub.3 = -532.7 f.sub.4 = -98.438 where, r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surfaces; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 29

A projection lens according to claim 22 as represented by the following data: ______________________________________ f = 103.9 Aperture ratio: 1:1.11 Magnification of projection: -7.932.sup.x Half angle of view: 27.1° r.sub.1 = 223.029 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -491.036 d.sub.2 = 90.0 r.sub.3 = 93.718 d.sub.3 = 24.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = -110.115 d.sub.4 = 3.0 r.sub.5 = -87.097 d.sub.5 = 5.0 n.sub.3 = 1.59501 L.sub.3 r.sub.6 = -144.756 d.sub.6 = 56.0 r.sub.7 = -48.366 d.sub.7 = 5.0 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5.0 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 = 8.0 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0 C.sub.2 = 0 C.sub.2 = 0 C.sub.4 = -0.14167 × 10.sup.-6 C.sub.4 = +0.16171 × 10.sup.-6 C.sub.4 = -0.22800 × 10.sup.-5 C.sub.6 = -0.22352 × 10.sup.-10 C.sub.6 = -0.17475 × 10.sup.-9 C.sub.6 = +0.19485 × 10.sup.-9 C.sub.8 = +0.97419 × 10.sup.-14 C.sub.8 = +0.59843 × 10.sup.-13 C.sub.8 = -0.65121 × 10.sup.-13 C.sub.10 = -0.19587 × 10.sup.-17 C.sub.10 = -0.13108 × 10.sup.-16 C.sub.10 = + 0.12473 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 312.2 f.sub.2 = 85.1 f.sub.3 = -379.8 f.sub.4 = -97.9 where r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surface; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.

Claim 30

A projection lens according to claim 22 as represented by the following data: ______________________________________ f = 103.5 Aperture ratio: 1:1.12 Magnification of projection: -7.952.sup.x Half angle of view: 28.4° r.sub.1 = 258.591 d.sub.1 = 11.0 n.sub.1 = 1.49380 L.sub.1 r.sub.2 = -383.684 d.sub.2 = 90.0 r.sub.3 = 97.238 d.sub.3 = 22.0 n.sub.2 = 1.62286 L.sub.2 r.sub.4 = -114.795 d.sub.4 = 3.0 r.sub.5 = -88.542 d.sub.5 = 5.0 n.sub.3 = 1.59048 L.sub.3 r.sub.6 = -130.879 d.sub.6 = 57.5 r.sub.7 = -49.159 d.sub.7 = 5.0 n.sub.4 = 1.49380 L.sub.4 r.sub.8 = ∞ r.sub.9 = ∞ d.sub.8 = 5.0 n.sub.5 = 1.45000 S r.sub.10 = ∞ d.sub.9 =0 8.0 n.sub.6 = 1.51872 G ______________________________________ __________________________________________________________________________ r.sub.1 (L.sub.1) r.sub.6 (L.sub.3) r.sub.7 (L.sub.4) __________________________________________________________________________ K = 1.0 K = 1.0 K = 0.0 C.sub.2 = 0.0 C.sub.2 = 0.0 C.sub.2 = 0.0 C.sub.4 = -0.15691 × 10.sup.-6 C.sub.4 = +0.95381 × 10.sup.-7 C.sub.4 = -0.22891 × 10.sup.-5 C.sub.6 = -0.40068 × 10.sup.-10 C.sub.6 = -0.73871 × 10.sup.-10 C.sub.6 = +0.12283 × 10.sup.-9 C.sub.8 = +0.21016 × 10.sup.-13 C.sub.8 = +0.12280 × 10.sup.-13 C.sub.8 = +0.84230 × 10.sup.-13 C.sub.10 = -0.37685 × 10.sup.-17 C.sub.10 = -0.33177 × 10.sup.-17 C.sub.10 = - 0.20592 × 10.sup.-16 __________________________________________________________________________ f.sub.1 = 314.6 f.sub.2 = 88.0 f.sub.3 = -481.2 f.sub.4 = -99.6 where, r 1 , r 2 , r 3 . . . are radii of curvature of the lens surfaces numbered in succession from the screen side; d 1 , d 2 , d 3 . . . are center-thicknesses and lens-to-lens distances of the first lens (L 1 ), second lens (L 2 ), third lens (L 3 ) and fourth lens (L 4 ); n 1 , n 2 , n 3 . . . are the refractive indexes to e-ray at 20° C. of the respective lenses; f 1 , f 2 , f 3 and f 4 are the focal lengths of the respective lenses; f is the focal length of the total system; C is apex curvature; K is a circular cone constant of the non-spherical surface; and C 2 , C 4 , C 6 , C 8 and C 10 are higher order constants of the non-spherical surface.