Projection lenses having color-correcting rear lens units
First Claim
1. A projection lens for forming an enlarged image of a pixelized panel on a screen, said projection lens having an optical axis, a long conjugate side, a short conjugate side, and an effective focal length f0, said lens, in order from the long conjugate side to the short conjugate side, comprising:
- (I) a first lens unit which, in order from the long conjugate side to the short conjugate side, comprises;
(A) a lens element LU1/N1 which;
(i) has a short conjugate surface which is concave towards the short conjugate side,(ii) comprises at least one aspheric surface, and(iii) has a negative optical power; and
(B) at least one other lens element; and
(II) a second lens unit having a positive power, said lens unit, in order from the long conjugate side to the short conjugate side, comprising;
(A) a first color-correcting doublet which, from the long conjugate side to the short conjugate side, has a positive-followed-by-negative form;
(B) a first positive lens element; and
(C) a second color-correcting doublet which, from the long conjugate side to the short conjugate side, has a negative-followed-by-positive form;
wherein;
(a) the first and second lens units are the only lens units of the projection lens;
(b) the projection lens has an aperture stop that is located between the first and second lens units;
(c) the projection lens has a field of view in the direction of the long conjugate which is greater than or equal to 75 degrees;
(d) the projection lens is telecentric on the short conjugate side;
(e) the projection lens has an effective back focal length BFL which satisfies the relationship;
BFL/f0≧
2.0; and
(f) the projection lens has a mechanical spacing S between two of its lens elements which satisfies the relationship;
S/f0≧
3.5,where the mechanical spacing is the smaller of the center-to-center distance and the edge-to-edge distance between the elements for an unfolded optical axis.
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Accused Products
Abstract
Projection lenses for use with pixelized panels (PP) are provided. The projection lenses have a first unit (U1) separated from a positive second unit (U2). The lenses are telecentric on the short conjugate side, have a large field of view in the direction of the long conjugate, have low aberration levels, and include a space between two of the lens elements making up the lens which is sufficient to accept a reflective surface (RS) for folding the lens'"'"' optical axis. The second or rear lens unit (U2) includes at least a first color-correcting lens subunit (SU2/CC1) which has a positive-followed-by-negative form and contributes to the correction of the chromatic aberrations of the projection lens, including the correction of lateral color.
84 Citations
27 Claims
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1. A projection lens for forming an enlarged image of a pixelized panel on a screen, said projection lens having an optical axis, a long conjugate side, a short conjugate side, and an effective focal length f0, said lens, in order from the long conjugate side to the short conjugate side, comprising:
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(I) a first lens unit which, in order from the long conjugate side to the short conjugate side, comprises; (A) a lens element LU1/N1 which; (i) has a short conjugate surface which is concave towards the short conjugate side, (ii) comprises at least one aspheric surface, and (iii) has a negative optical power; and (B) at least one other lens element; and (II) a second lens unit having a positive power, said lens unit, in order from the long conjugate side to the short conjugate side, comprising; (A) a first color-correcting doublet which, from the long conjugate side to the short conjugate side, has a positive-followed-by-negative form; (B) a first positive lens element; and (C) a second color-correcting doublet which, from the long conjugate side to the short conjugate side, has a negative-followed-by-positive form; wherein; (a) the first and second lens units are the only lens units of the projection lens; (b) the projection lens has an aperture stop that is located between the first and second lens units; (c) the projection lens has a field of view in the direction of the long conjugate which is greater than or equal to 75 degrees; (d) the projection lens is telecentric on the short conjugate side; (e) the projection lens has an effective back focal length BFL which satisfies the relationship;
BFL/f0≧
2.0; and(f) the projection lens has a mechanical spacing S between two of its lens elements which satisfies the relationship;
S/f0≧
3.5,where the mechanical spacing is the smaller of the center-to-center distance and the edge-to-edge distance between the elements for an unfolded optical axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A projection lens for forming an enlarged image of a pixelized panel on a screen, said projection lens having an optical axis, a long conjugate side, a short conjugate side, and an effective focal length f0, said lens, in order from the long conjugate side to the short conjugate side, comprising:
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(I) a first lens unit which, in order from the long conjugate side to the short conjugate side, comprises; (A) a first lens subunit which comprises a lens element LU1/N1 which; (i) has a short conjugate surface which is concave towards the short conjugate side, (ii) comprises at least one aspheric surface, and (iii) has a negative optical power; and (B) a second lens subunit which comprises at least one lens element; and (II) a second lens unit having a positive power, said lens unit, in order from the long conjugate side to the short conjugate side, comprising; (A) a first color-correcting subunit, said subunit having an effective V-value Ve/CC1 and comprising a color-correcting doublet which, in order from the long conjugate side to the short conjugate side, comprises; (i) a positive lens element having a V-value Vp/CC1, a Q-value Qp/CC1, and a short conjugate radius RI1; and (ii) a negative lens element having a V-value Vn/CC1 and a Q-value Qn/CC1; and (B) a second color-correcting subunit, said subunit having an effective V-value Ve/CC2 and comprising a color-correcting doublet which, in order from the long conjugate side to the short conjugate side, comprises; (i) a negative lens element having a V-value Vn/CC2 and a Q-value Qn/CC2; and (ii) a positive lens element having a V-value Vp/CC2, a Q-value Qp/CC2, and a long conjugate radius RI2; wherein; (a) the first and second lens units are the only lens units of the projection lens; (b) the projection lens has an aperture stop that is located between the first and second lens units; (c) the projection lens has a field of view in the direction of the long conjugate which is greater than or equal to 75 degrees; (d) the projection lens is telecentric on the short conjugate side; (e) the projection lens has an effective back focal length BFL which satisfies the relationship;
BFL/f0≧
2.0;(f) the projection lens has a mechanical spacing S between two of its lens elements which satisfies the relationship;
S/f0≧
3.5,where the mechanical spacing is the smaller of the center-to-center distance and the edge-to-edge distance between the elements for an unfolded optical axis; and (g) Ve/CC1, Vp/CC1, Qp/CC1, RI1, Vn/CC1, Qn/CC1, Ve/CC2, Vn/CC2, Qn/CC2, Vp/CC2, Qp/CC2, and RI2 satisfy the relationships;
|Ve/CC1|<
|Ve/CC2|,
0.25≦
|RI1/(Vp/CC1−
Vn/CC1)|≦
0.60,
Qp/CC1>
0,
0.35≦
|RI2/(Vp/CC2−
Vn/CC2)|≦
1.4,
Qp/CC2>
0, and
Qn/CC1<
0 and/or Qn/CC2<
0.- View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification