Reflecting optical system for projection television

Claim 2

In a projection television system including a light emitting target capable of providing a video image of a high resolution definition of 1,000 T.V. lines and a screen for realizing the projected video image for example generated by an electron gun exciting the target, an improvement in a reflecting optical system which defines an optical path for projecting the video image on the screen, comprising; a concave mirror for reflecting the image toward the screen; a meniscus lens located in the optical path between the concave mirror and the screen; at least one optical aspherical surface in the optical path, whereby the aspherical surface coefficient, C 2 ; radius of curvature of the inside surface of the meniscus lens, R, and the focal length, f, of the entire optical system satisfies the following conditions; 10.sup.-2 /f.sup.4 <|C.sub.2 |<10.sup.2 /f.sup.4 ( 1) 0.6f<|R|<1.2f (2) these conditions providing a projection television system with a resolution of 1,000 T.V. lines on the screen.

Claim 3

The invention of claim 1 wherein the meniscus lens is convex towards the screen and located at the screen side of the aspherical surface along the optical path.

Claim 4

The invention of claim 1 further comprising a vacuum tube for enclosing the electron and the light emitting target, wherein the aspherical surface and the meniscus lens are located outside the vacuum tube.

Claim 5

The invention of claim 1 wherein a compensating plate has the aspherical surface.

Claim 6

In a projection television system including a light emitting target, a screen for realizing a projected video image for example, generated by an electron gun exciting the target and a concave mirror relatively positioned to the light emitting target for reflecting the video image formed on the target towards the screen, an optical system essential to the improvement on the T.V. resolution of the video image on the screen consisting of: an optical compensating plate having at least one aspherical surface located on an optical path between the concave mirror and the screen, and a meniscus lens convex to the screen side located on an optical path between the optical compensating plate and the screen, whereby a relatively uniform correction of aberration is provided across the image displayed on the screen, in which the aspherical surface coefficient, C 2 , radius of curvature of the inside surface of the meniscus lens, R, and the focal length, f, of the entire optical system satisfy the following conditions: 10.sup.-2 /f.sup.4 <|C.sub.2 |<10.sup.2 /f.sup.4 ( 1) 0.6f<|R|<1.2f (2)

Claim 7

In a projection television system including a light emitting target, a screen for realizing a projected video image for example, generated by an electron gun exciting the target and a concave mirror relatively positioned to the light emitting target for reflecting the video image formed on the target towards the screen, an optical system essential to the improvement on the T.V. resolution of the video image on the screen consisting of: an optical compensating plate having at least one aspherical surface located on an optical path between the concave mirror and the screen, and a meniscus lens convex to the screen side located on an optical path between the optical compensating plate and the screen, whereby a relatively uniform correction of aberration is provided across the image displayed on the screen, in which the aspherical surface coefficient, C 2 , radius of curvature of the inside surface of the meniscus lens, R, and the focal length, f, of the entire optical system satisfy the following conditions: 10.sup.-2 /f.sup.4 <|C.sub.2 |<10.sup.2 /f.sup.4 ( 1) 0.6f<|R|<1.2f (2)

Claim 8

The invention of claim 5 further comprising a vacuum tube for enclosing the electron gun and the light emitting target, wherein the optical compensating plate and the meniscus lens are located outside the vacuum tube.

Claim 9

The invention of claim 5, wherein the optical compensating plate has only one aspherical surface.

Claim 10

The invention of claim 7, wherein the aspherical surface is located on the concave mirror side.

Claim 11

An optical projection system having an optical axis for magnifying a video image of a fluorescent target television system having the following design parameters; ______________________________________ f = 100.0 Fno = 0.7 2ω = 45° Radius of Axial Refractive Abbe Curvature Distance Index Number ______________________________________ r.sub.1 ' 104.43 d.sub.1 ' 15.6 nd.sub.1 ' 1.5168 νd.sub.1 ' 64.0 r.sub.2 ' 89.02 d.sub.2 ' 82.6 r.sub.3 ' ∞ (aperture stop) d.sub.3 ' 10.0 nd.sub.2 ' 1.4914 νd.sub.2 ' 57.8 r.sub.4 ' -2511.9 (aspherical surface) d.sub.4 ' 52.1 r.sub.5 ' ∞ d.sub.5 ' 8.6 nd.sub.3 ' 1.5168 νd.sub.3 ' 64.0 r.sub.6 ' ∞ d.sub.6 ' 149.9 r.sub.7 ' -207.48 (reflecting concave mirror) d.sub.7 ' -111.3 r.sub.8 ' -96.83 (fluorescent target) ______________________________________ wherein the aspherical surface is defined as; ##EQU2## where X is an axial distance measured from the vertex of the fourth surface, r 4 ' toward the reflecting concave mirror; Y is the height from the optical axis to a given point on the aspherical surface; C 0 is the paraxial radius of curvature and the values of the aspherical surface coefficients C 2 , C 3 , C 4 and C 5 are as follows: C 2 =0.439838×10 -7 C 3 =-0.305694×10 -11 C 4 =0.129572×10 -14 C 5 =0.140204×10 -18 .

Claim 12

An optical projection system having an optical axis for magnifying a video image of a fluorescent target television system having the following design parameters; ______________________________________ f = 100.0 Fno = 0.7 2ω = 45° Radius of Axial Refractive Abbe Curvature Distance Index Number ______________________________________ r.sub.1 ' 104.43 d.sub.1 ' 15.6 nd.sub.1 ' 1.5168 νd.sub.1 ' 64.0 r.sub.2 ' 89.02 d.sub.2 ' 82.6 r.sub.3 ' ∞ (aperture stop) d.sub.3 ' 10.0 nd.sub.2 ' 1.4914 νd.sub.2 ' 57.8 r.sub.4 ' -2511.9 (aspherical surface) d.sub.4 ' 52.1 r.sub.5 ' ∞ d.sub.5 ' 8.6 nd.sub.3 ' 1.5168 νd.sub.3 ' 64.0 r.sub.6 ' ∞ d.sub.6 ' 149.9 r.sub.7 ' -207.48 (reflecting concave mirror) d.sub.7 ' -111.3 r.sub.8 ' -96.83 (fluorescent target) ______________________________________ wherein the aspherical surface is defined as; ##EQU2## where X is an axial distance measured from the vertex of the fourth surface, r 4 ' toward the reflecting concave mirror; Y is the height from the optical axis to a given point on the aspherical surface; C 0 is the paraxial radius of curvature and the values of the aspherical surface coefficients C 2 , C 3 , C 4 and C 5 are as follows: C 2 =0.439838×10 -7 C 3 =-0.305694×10 -11 C 4 =0.129572×10 -14 C 5 =0.140204×10 -18 .