JP5231286B2 - Projection zoom lens, projector apparatus, and imaging apparatus - Google Patents

Description

  The present invention relates to a projection zoom lens, a projector device, and an imaging device.

  A projector device that enlarges and projects an image displayed on an image display device using a liquid crystal panel or a micromirror using a projection lens is widely used for displaying data in a computer.

  As a projection lens in a projector device, a “projection zoom lens” having a zoom function is generally used so that an optimal display image size can be easily realized on a screen. Various types from a zoom type to a telephoto zoom type are used.

The projection zoom lens generally requires the following attributes.
Since the light beams whose intensity has been modulated by the image display device are often synthesized by color synthesis means such as a dichroic prism or a dichroic mirror, a space for arranging color synthesis means between the lens on the object side and the image display device "Having a relatively long back focus" so that

  Since the color shading is likely to occur when the “angle of light incident on the color combining means” varies depending on the angle of view when combining the optical paths of the respective color lights, the light incident on the projection zoom lens from the light source side is “with respect to the optical axis. It is preferable to use a “light beam that is nearly parallel”.

  In this case, in order to obtain high light utilization efficiency with low power, “the telephoto lens should have telecentricity on the reduction side, that is, the image display device side so that the parallel light flux can be efficiently taken into the projection zoom lens”.

  It must be a “bright lens with a small F number” so as to capture as much light as possible from the light source side so that a bright image can be displayed even with a low-power light source.

  When three colors are superimposed on the screen, if the pixels of each color shift from each other, a good color image cannot be realized, and edges such as green, blue, and red appear on the edge of the projected image, and the image Quality is impaired. To prevent this, the chromatic aberration of magnification is kept small.

  The distortion is limited to an allowable range so that the contour of the projected image is not distorted and unsightly.

  In order to faithfully reproduce the image displayed on the image display device in the enlarged projection image, it has high MTF characteristics and resolution characteristics.

  It is desirable that axial chromatic aberration is also suppressed to be low so that it can be applied to an interchangeable lens projector.

  Improvement of such attributes has been pursued from the past, but further improvement is required and its realization is becoming increasingly difficult.

  In particular, the present invention contemplates the realization of a projection zoom lens used in a high-intensity projector device used in a relatively large meeting room or the like, but in a large meeting room, a projector body is installed on one side of the room. Generally, an enlarged image is projected onto a screen installed on the opposite side.

For this reason, such a projection zoom lens inevitably has a “long focal length”.
A lens having a “long focal length” can be easily realized by a conventionally known telephoto type or its derivative type. However, in the projection lens for a projector device as described above, an image for each color is synthesized. For this reason, the conventional lens has a problem that it is difficult to achieve a desired performance.

  Various projection zoom lenses have been proposed in the past, and two typical examples are shown in Patent Documents 1 and 2.

  This invention makes it a subject to provide the zoom lens for projection which can improve the above-mentioned various attributes favorably.

The projection zoom lens according to the present invention is a “projection zoom lens for enlarging and projecting a planar image with a variable magnification”.

  The “planar image” is an image displayed on an image display device using a liquid crystal panel or a micromirror, and is an “object” in the image formation of the projection zoom lens.

  The projection zoom lens according to the first aspect includes a first lens group to a seventh lens group in order from the magnification side.

In these first to seventh lens groups, the first lens group has a negative refractive power, the third lens group, the fourth lens group, and the fifth lens group both have a positive refractive power, and the sixth lens group has a negative refractive power. Refracting power, the seventh lens group has positive refracting power. The second lens group has “negative or positive refractive power”.
At the time of zooming, the distance between the lens groups of the first to seventh lens groups, that is, the distance between adjacent lens groups changes.
In particular, as shown in the examples described later, all of the third to sixth lens groups move away from the seventh lens group upon zooming from the wide-angle end to the telephoto end.

  That is, the power distribution of the projection zoom lens according to claim 1 is “negative / negative / positive / positive / positive / negative / positive” from the enlargement side (image side) to the reduction side (planar image side). (Claim 2) or "Negative / Positive / Positive / Positive / Positive / Negative / Positive" (Claim 3).

  The degree of freedom in design is increased by giving positive and negative degrees of freedom to the refractive power of the second lens group.

Preferably, in the zoom lens for projection according to any one of claims 1 to 3, "the seventh lens group does not change a position with respect to a planar image as an object" upon zooming (claim 4).
Preferably, in the zoom lens for projection according to any one of claims 1 to 4, "the first lens group does not change its position with respect to the planar image" upon zooming (claim 5).

  If the "seventh lens group closest to the object side is a fixed group" as in claim 4 and "the first lens group closest to the image side is also a fixed group" as in claim 5, then a projection zoom lens And the positional relationship with respect to the light source, the image display device, the color synthesizing means, etc. are fixed, and the handling of the projector apparatus and imaging apparatus equipped with the projection zoom lens is improved.

  In the projection zoom lens according to any one of claims 1 to 5, it is preferable that the sixth lens group includes a “surface having the smallest absolute value of the radius of curvature of the refractive surface in the entire system” (claim). Item 6).

The projection zoom lens according to any one of claims 1 to 6, wherein the focal length of the third lens group is f3, the focal length of the fourth lens group is f4, and the focal length of the fifth lens group is f5. :
(1) (1 / f5)-(1 / f3)> 0
(2) (1 / f5)-(1 / f4)> 0
Is preferably satisfied (claim 7).
The projection zoom lens according to any one of claims 1 to 7, wherein the third lens group and the fifth lens group are each composed of "positive lenses only", and the fourth lens group is "one or more positive lenses". And one or more negative lenses ”(claim 8).

The projection zoom lens according to any one of claims 1 to 8, further comprising: a focal length at the telephoto end in the entire system: fT; a focal length at the wide angle end in the entire system: fW; Distance to the far part: Ymax, the longest lens length in the entire zoom range: OAL, the condition:
(3) 5 · fT / fW <OAL / Ymax <8 · fT / fW
Is preferably satisfied (claim 9).
In the zoom lens for projection according to any one of claims 1 to 9, the third lens group can consist of "only one positive lens" (claim 10).

  In the projection zoom lens according to any one of claims 1 to 10, it is preferable that the fourth lens group has “a configuration in which a positive lens and a negative lens are arranged separately or joined in order from the magnification side”. (Claim 11).

  In the zoom lens for projection according to any one of claims 1 to 11, it is preferable that the fifth lens group has a configuration "including at least two positive meniscus lenses having a convex surface facing the enlargement side" (claim 12). ).

  It is preferable that the zoom lens for projection according to any one of claims 1 to 12 includes “a cemented lens having a cemented surface convex toward the reduction side” in the sixth lens group (claim 13).

  In any one of the zoom lenses for projection according to any one of claims 1 to 13, it is preferable that the first lens group has a configuration in which “a positive lens and a negative lens are separately or cemented” (claim 14).

  The projection zoom lens according to any one of claims 1 to 14 can be “a telecentric optical system in which the pupil position on the planar image side is almost infinite” (claim 15).

  A projector device of the present invention is a projector device (Claim 16) equipped with the projection zoom lens according to any one of Claims 1 to 15, and the imaging device of the present invention is any of Claims 1 to 15 An image pickup apparatus using the zoom lens according to 1 for image pickup (claim 17).

To supplement the explanation, in the projection zoom lens according to the present invention, it is easy to obtain a long back focus by giving a negative refractive power to the first lens group on the most enlargement side.
Further, by setting the third, fourth, and fifth lens groups closer to the enlargement side to be “positive lens groups”, a thick light beam entering a long-focus lens having a small F value can be “squeezed while suppressing the occurrence of aberrations”. "be able to.

  Further, by making the refractive power of the sixth lens group negative, it is possible to cancel various aberrations caused by the “positive refractive power of the composite system of the first to fifth lens groups” and It is possible to “make the pupil viewed from the reduction side to be an almost infinite position” and to easily match the illumination optical system including the light source.

  As described in claim 4, by not moving the first lens group as a fixed group at the time of zooming, complication of the lens frame can be avoided and low cost can be realized.

  Since the space near the focal point on the reduction side is “narrowed by the image display device, the polarization adjusting member, etc.”, the member that moves the seventh lens group is formed by setting the seventh lens group as a fixed group. By making it unnecessary, it is effective for miniaturization of a projector device or the like.

  Regarding the relationship between the third to fifth lens groups having positive refractive power, each of the third lens group and the fourth lens group is refracted with respect to the fifth lens group in consideration of the height of the axial ray height. By reducing the force, it is possible to “obtain a better image without generating large aberrations”. Conditions (1) and (2) are conditions for “realizing such a situation”. It is.

  If the lower limit of condition (1) is exceeded, various aberrations due to the “positive refracting power” of the third lens group will increase, making correction in other groups difficult. When the lower limit of the condition (2) is exceeded, the positive refractive power of the fourth lens group becomes relatively large with respect to the positive refractive power of the fifth lens group, and “occurrence of various aberrations increases”. It becomes difficult to correct in the group.

Since the third, fourth, and fifth lens groups all have a positive refractive power, they should basically be composed of a positive lens from the viewpoint of cost, but axial chromatic aberration can be achieved only with a positive lens. It is easy to fall into the lack of correction.
In order to avoid this, it is preferable to “include a negative lens in the fourth lens group” as in claim 7. By doing so, axial chromatic aberration, spherical aberration and the like can be corrected more favorably.

  In particular, by arranging the fourth lens group separately from the magnification side in the order of the positive lens and the negative lens, or by joining these positive and negative lenses with the positive lens on the magnification side, aberrations such as chromatic aberration can be reduced. Best corrected.

  The fifth lens group is configured to include “two or more meniscus lenses having a convex surface facing the enlargement side” to thereby disperse the refractive power in a balanced manner and obtain good image performance.

  Further, since the sixth lens group is a “group with the lowest axial ray height”, a flat image surface can be obtained by reducing the Petzval sum by “disposing a strong negative surface” in the sixth lens group. Can be easily obtained. That is, as in the twelfth aspect, it is preferable to arrange “a surface having the smallest absolute value of the radius of curvature in the entire system” in the sixth lens group.

  Further, by including “a cemented lens having a cemented surface convex toward the reduction side” in the sixth lens group, it is possible to easily correct longitudinal chromatic aberration and lateral chromatic aberration simultaneously.

  When the first lens group has “large chromatic aberration”, the axial chromatic aberration, that is, “the positional relationship of red, green, and blue” easily changes during zooming. Although it is possible to reduce such chromatic aberration with only a negative lens by “selecting an appropriate lens material”, chromatic aberration is corrected in the first lens group in order to better suppress chromatic aberration. It is more desirable.

  For this purpose, as in claim 13, it is preferable to include “one or more positive lenses and one or more negative lenses” in the first lens group.

  With the recent increase in projection lens magnification, the lens tends to increase in size, but the projection zoom lens according to the present invention has a zoom ratio (the ratio of the focal length at the telephoto end to the focal length at the wide-angle end). On the other hand, by setting an appropriate relationship between the "substantial size of the image display surface" and the total lens length, it is possible to "ensure sufficient imaging performance in the entire zoom range while being compact." .

That is, the condition (3) is a condition for setting the appropriate relationship.
When the lower limit of the condition (3) is exceeded, each lens group needs to have a large refractive power, which causes a large aberration. On the contrary, if the upper limit of the condition (3) is exceeded, the total lens length becomes redundant, leading to an increase in the size of the projector device body and an increase in cost.

Since the projection zoom lens according to the present invention is effective for a projector apparatus, a projector apparatus with good projection performance can be realized by installing the zoom lens.
In addition, since the planar image and the projected image are conjugate with each other in the projection zoom lens, the image on the projected image is captured by arranging the light receiving surface of the image sensor on the “optically equivalent surface” with the planar image. It can also be used as a photographing lens that captures an image of an enlarged landscape, an object, etc., and an imaging device according to claim 17 can be realized.

  As described above, according to the present invention, a novel projection lens / projector apparatus / imaging apparatus can be realized. The projection lens of the present invention has good performance as will be described later in the embodiments, and by using this, a projector device and an imaging device with good performance can be realized.

2 is a cross-sectional view of a lens of Example 1 at a wide angle end. FIG. 2 is a cross-sectional view of a lens of Example 1 at a telephoto end. FIG. FIG. 4 is an aberration diagram at the wide-angle end of the lens according to Example 1; FIG. 4 is an aberration diagram for the lens of Example 1 at the telephoto end. 6 is a cross-sectional view at the wide-angle end of the lens of Example 2. FIG. 6 is a cross-sectional view of a lens of Example 2 at a telephoto end. FIG. FIG. 6 is an aberration diagram at the wide-angle end of the lens according to Example 2. 6 is an aberration diagram at the telephoto end of the lens of Example 2. FIG. 6 is a cross-sectional view of a lens according to Example 3 at a wide angle end. FIG. 6 is a cross-sectional view of a lens of Example 3 at a telephoto end. FIG. FIG. 6 is an aberration diagram at the wide-angle end of the lens according to Example 3. FIG. 6 is an aberration diagram at the telephoto end of the lens according to Example 3; 6 is a cross-sectional view of a lens according to Example 4 at a wide angle end. FIG. 6 is a cross-sectional view of a lens according to Example 4 at a telephoto end. FIG. FIG. 10 is an aberration diagram at the wide-angle end of the lens according to Example 4; FIG. 10 is an aberration diagram at the telephoto end of the lens in Example 4;

  1 and 2 show one embodiment of a projection zoom lens.

  This embodiment relates to Example 1 described later. FIG. 1 shows the lens arrangement at the telephoto end, and FIG. 2 shows the lens arrangement at the wide-angle end.

  The symbol SCR on the left side of the figure indicates a “screen”, that is, a projection surface, and the DV on the right side of the figure is an image display surface of an image display device such as a liquid crystal panel. A “planar image” is displayed on the image display surface DV. Is done. The above points are the same in other embodiments described below.

The projection zoom lens according to the embodiment shown in FIGS. 1 and 2 is a projection zoom lens that enlarges a planar image at a variable magnification and forms a projection image. The projection zoom lens is arranged in order from the enlargement side (left side in the figure). A lens group G1 to a seventh lens group G7 are arranged.
The first lens group G1 has a negative refractive power, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 all have a positive refractive power, the sixth lens group G6 has a negative refractive power, and a seventh lens group. G7 has a positive refractive power, and the second lens group G2 has a "negative refractive power".

  The projection zoom lens whose embodiment is shown in FIGS. 5 and 6 relates to Example 2 described later. FIG. 5 shows the lens arrangement at the telephoto end, and FIG. 6 shows the lens arrangement at the wide-angle end.

The projection zoom lens according to this embodiment is a projection zoom lens that magnifies and projects a planar image with a variable magnification. The first lens group G1 to the seventh lens lens are sequentially arranged from the enlargement side (left side in the figure). A lens group G7 is arranged.
The first lens group G1 has a negative refractive power, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 all have a positive refractive power, the sixth lens group G6 has a negative refractive power, and a seventh lens group. G7 has a positive refractive power, and the second lens group G2 has a "negative refractive power".

  The projection zoom lens whose embodiment is shown in FIGS. 9 and 10 relates to Example 3 described later, FIG. 9 shows the lens arrangement at the telephoto end, and FIG. 10 shows the lens arrangement at the wide-angle end.

The projection zoom lens according to this embodiment is a projection zoom lens that magnifies and projects a planar image with a variable magnification. The first lens group G1 to the seventh lens lens are sequentially arranged from the enlargement side (left side in the figure). A lens group G7 is arranged.
The first lens group G1 has a negative refractive power, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 all have a positive refractive power, the sixth lens group G6 has a negative refractive power, and a seventh lens group. G7 has a positive refractive power, and the second lens group G2 has a “positive refractive power”.

  The projection zoom lens whose embodiment is shown in FIGS. 13 and 14 relates to Example 4 described later, FIG. 5 shows the lens arrangement at the telephoto end, and FIG. 6 shows the lens arrangement at the wide-angle end.

The projection zoom lens according to this embodiment is a projection zoom lens that magnifies and projects a planar image with a variable magnification. The first lens group G1 to the seventh lens lens are sequentially arranged from the enlargement side (left side in the figure). A lens group G7 is arranged.
The first lens group G1 has a negative refractive power, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 all have a positive refractive power, the sixth lens group G6 has a negative refractive power, and a seventh lens group. G7 has a positive refractive power, and the second lens group G2 has a "negative refractive power".

  Hereinafter, four specific examples of the projection zoom lens will be described.

  In Examples 1 to 4 below, each symbol has the following meaning.

i-th surface (lens surface and diaphragm surface) counted from the magnification side
IMG image display device side
Ri The radius of curvature of the i-th surface from the enlarged side
Di Axis upper surface distance from the i-th surface to the (i + 1) -th surface counted from the enlargement side
The distance from the Do screen to the first lens surface
J jth lens from the magnifying side
Nj Refractive index with respect to d-line of the jth lens counted from the magnification side
νj Abbe number of the jth lens from the magnification side
PR color synthesis prism
The “calculation reference wavelength” is 550 nm (green).
"Example 1"
i R D j N ν
0 ∞ 5800
1 380.319 2.693 1 1.80518 25.5
2 58063.394 0.200
3 394.275 2.300 2 1.62041 60.3
4 44.351 Variable
5 -1339.437 2.200 3 1.51680 64.2
6 51.817 4.230 4 1.84666 23.8
7 92.646 Variable
8 54.863 5.263 5 1.49700 81.6
9 176.077 Variable
10 116.899 8.091 6 1.61800 63.4
11 -57.989 2.200 7 1.84666 23.8
12 -118.672 Variable
13 50.462 4.565 8 1.61800 63.4
14 188.487 0.200
15 25.031 5.125 9 1.61800 63.4
16 40.527 Variable
17 27.708 2.051 10 1.62374 47.1
18 17.211 5.876
19 (aperture surface) ∞ 4.170
20 -138.800 3.347 11 1.49700 81.6
21 -29.654 1.900 12 1.61310 44.4
22 34.756 8.335
23 -247.210 2.546 13 1.90366 31.3
24 -57.994 2.563
25 -19.964 1.900 14 1.69895 30.1
26 58.885 6.868 15 1.49700 81.6
27 -35.146 0.200
28 205.383 7.875 16 1.49700 81.6
29 -33.705 Variable
30 247.189 5.621 17 1.84666 23.8
31 -81.849 9.000
32 ∞ 29.000 PR 1.51680 64.2
33 ∞ 9.000
IMG ∞ 0.000.

"Variable amount"
Wide-angle end Middle Telephoto end
Focal length 45.79 56.24 73.50
Variable group spacing
D4 29.470 24.784 11.793
D7 13.907 4.096 1.500
D9 6.295 7.596 1.500
D12 1.000 5.277 18.008
D16 1.000 2.330 4.198
D29 1.000 8.588 15.673.

"Parameter values for conditional expressions"
Condition (1) 0.0135
Condition (2) 0.0115
Condition (3) fT / fW = 1.605, OAL / Ymax = 9.108.

"Example 2"
i R D j N ν
O ∞ 6000.000
1 446.598 5.505 1 1.76182 26.6
2 -156.658 5.383
3 -115.480 2.300 2 1.61800 63.4
4 57.268 Variable
5 158.897 2.200 3 1.51680 64.2
6 52.092 1.900 4 1.84666 23.8
7 52.603 Variable
8 54.035 4.761 5 1.49700 81.6
9 122.567 Variable
10 54.755 9.968 6 1.61800 63.4
11 -67.625 2.200 7 1.84666 23.8
12 -129.060 Variable
13 33.271 4.219 8 1.61800 63.4
14 51.141 0.200
15 31.412 4.813 9 1.61800 63.4
16 66.883 Variable
17 22.000 1.900 10 1.61310 44.4
18 15.474 5.343
19 (Aperture) ∞ 0.958
20 -85.468 5.473 11 1.49700 81.6
21 -45.435 2.801 12 1.61310 44.4
22 31.697 7.023
23 -171.907 2.641 13 1.90366 31.3
24 -44.012 2.379
25 -17.485 1.900 14 1.69895 30.1
26 45.750 6.647 15 1.49700 81.6
27 -38.364 0.200
28 181.262 8.514 16 1.49700 81.6
29 -29.966 Variable
30 306.175 5.930 17 1.84666 23.8
31 -69.411 9.000
32 ∞ 26.000 PR 1.51680 64.2
33 ∞ 8.194
IMG: ∞.

"Variable amount"
Wide-angle end Middle Telephoto end
Focal length 47.800 58.730 76.76
Variable group spacing
D4 7.463 5.489 8.881
D7 15.271 5.161 1.527
D9 15.905 16.884 1.500
D12 1.000 5.510 11.366
D16 1.000 2.638 4.949
D29 1.000 5.957 13.417.

"Parameter values for conditional expressions"
Condition (1) 0.0125
Condition (2) 0.0036
Condition (3) fT / fW = 1.605, OAL / Ymax = 8.713.

"Example 3"
i R D j N ν
O ∞ 6000.000
1 252.097 3.480 1 1.84666 23.8
2 141.430 1.818
3 253.430 2.300 2 1.62041 60.3
4 63.935 Variable
5 -1063.932 2.200 3 1.51680 64.2
6 60.251 8.964 4 1.84666 23.8
7 211.430 Variable
8 121.782 5.537 5 1.49700 81.6
9 704.524 Variable
10 96.623 14.976 6 1.61800 63.4
11 -72.076 2.200 7 1.84666 23.8
12 -176.462 Variable
13 39.291 6.305 8 1.61800 63.4
14 137.635 0.200
15 29.075 4.995 9 1.61800 63.4
16 49.915 Variable
17 60.343 1.900 10 1.62374 47.1
18 18.525 6.086
19 (Aperture) ∞ 2.891
20 246.428 4.649 11 1.49700 81.6
21 -30.583 5.500 12 1.61310 44.4
22 35.649 8.134
23 -101.475 4.661 13 1.90366 31.3
24 -48.940 2.091
25 -21.265 1.900 14 1.69895 30.1
26 97.556 5.637 15 1.49700 81.6
27 -37.235 0.200
28 2455.928 7.150 16 1.49700 81.6
29 -29.507 Variable
30 274.080 5.500 17 1.84666 23.8
31 -81.816 0.000
32 ∞ 29.000 PR 1.51860 64.2
33 ∞ 22.077
IMG ∞ 0.000.

"Variable amount"
Wide-angle end Middle Telephoto end
Focal length 47.88 58.83 76.95
Variable group spacing
D4 31.753 23.325 14.358
D7 29.646 13.027 1.500
D9 3.635 13.078 8.252
D12 1.000 9.232 25.423
D16 1.748 2.391 3.340
D29 1.858 8.587 16.767.

"Parameter values for conditional expressions"
Condition (1) 0.0177
Condition (2) 0.0132
Condition (3) fT / fW = 1.607, OAL / Ymax = 11.39.

Example 4
i R D j N ν
0 ∞ 6000.000
1 60.614 2.300 1 1.62041 60.3
2 36.535 Variable
3 -190.062 2.200 2 1.51680 64.2
4 55.715 4.008 3 1.84666 23.8
5 92.850 Variable
6 52.041 5.984 4 1.49700 81.6
7 166.325 Variable
8 108.678 7.877 5 1.61800 63.4
9 -63.439 2.200 6 1.84666 23.8
10 -114.866 Variable
11 34.226 5.084 7 1.61800 63.4
12 70.286 0.200
13 25.462 5.227 8 1.61800 63.4
14 45.538 Variable
15 23.875 1.900 9 1.62374 47.1
16 15.022 5.383
17 (Aperture) ∞ 1.656
18 -157.296 3.017 10 1.49700 81.6
19 -38.744 1.900 11 1.61310 44.4
20 31.532 7.471
21 -261.966 2.690 12 1.90366 31.3
22 -50.915 2.917
23 -17.921 1.900 13 1.69895 30.1
24 50.324 7.294 14 1.49700 81.6
25 -37.939 0.200
26 215.518 9.292 15 1.49700 81.6
27 -30.453 Variable
28 226.681 5.921 16 1.84666 23.8
29 -80.287 8.000
30 ∞ 25.000 PR 1.51680 64.2
31 ∞ 5.000
IMG ∞ 0.000.

"Variable amount"
Wide-angle end Middle Telephoto end
Focal length 47.80 58.73 76.76
Variable group spacing D2 15.644 16.559 14.468
D5 23.091 9.945 1.500
D7 13.636 12.547 1.500
D10 1.000 7.363 20.165
D14 1.000 1.827 2.752
D27 1.000 7.128 14.986.

"Parameter values for conditional expressions"
Condition (1) 0.0146
Condition (2) 0.0120
Condition (3) fT / fW = 1.605, OAL / Ymax = 5.635.

  FIG. 3 shows aberration diagrams at the wide-angle end related to Example 1, and FIG. 4 shows aberration diagrams at the telephoto end related to Example 1. In these aberration diagrams, “G” indicates an aberration at a wavelength of 550.0 nm, “R” indicates an aberration at a wavelength of 620.0 nm, and “B” indicates an aberration at a wavelength of 470.0 nm. “S” indicates a sagittal image plane at a wavelength of 550.0 nm, and “T” indicates a tangential image plane at a wavelength of 550.0 nm. The same applies to other aberration diagrams.

  FIG. 7 shows aberration diagrams at the wide-angle end related to Example 2, and FIG. 8 shows aberration diagrams at the telephoto end related to Example 2. FIG. 11 shows aberration diagrams at the wide-angle end related to Example 3, and FIG. 12 shows aberration diagrams at the telephoto end related to Example 3. FIG. 15 shows aberration diagrams at the wide-angle end related to Example 4, and FIG. 16 shows aberration diagrams at the telephoto end related to Example 1.

  As shown in these aberration diagrams, each of the examples has good performance even though an aspheric surface is not adopted.

  In each of the embodiments, the zoom lens for projection does not change the position of the seventh lens group G7 with respect to the planar image as the object during zooming, and the first lens group G1 Does not change position.

  In each example, the sixth lens group G6 includes a “surface having the smallest absolute value of the radius of curvature of the refractive surface in the entire system”. The third lens group G3, the fifth lens group G5, Are composed of only positive lenses, and the fourth lens group G4 is a “junction lens” in which one or more positive lenses and one or more negative lenses are cemented in this order from the magnification side, and the third lens group G3 The fifth lens group G5 includes only one positive lens, and the fifth lens group G5 includes two positive meniscus lenses having a convex surface directed toward the enlargement side. The sixth lens group G6 has a “shape where the cemented surface is convex toward the reduction side. Includes "junction lens".

  Each of the embodiments is a “telecentric optical system in which the pupil position on the planar image side is almost infinite”.

  Accordingly, it is possible to realize a projector apparatus or an imaging apparatus with good performance by mounting any one of the projection zoom lenses in these embodiments.

G1 first lens group
G2 second lens group
G3 Third lens group
G4 4th lens group
G5 5th lens group
G6 6th lens group
G7 7th lens group
SCR screen surface
Image display surface of DV image display device
PR color synthesis prism

Japanese Patent Laid-Open No. 2004-70306 JP 2001-108900 A

Claims (17)

There is a projection zoom lens that enlarges a planar image with variable magnification and forms a projection image,
In order from the magnification side, the first lens group to the seventh lens group are arranged,
The first lens group has a negative refractive power, the third lens group, the fourth lens group, and the fifth lens group all have a positive refractive power, the sixth lens group has a negative refractive power, and the seventh lens group has a positive refractive power. Have
The second lens group has negative or positive refractive power,
A zoom lens for projection, wherein the distance between the lens groups of the first to seventh lens groups changes upon zooming. The projection zoom lens according to claim 1,
A projection zoom lens, wherein the second lens group has negative refractive power. The projection zoom lens according to claim 1,
A projection zoom lens, wherein the second lens group has a positive refractive power. The projection zoom lens according to any one of claims 1 to 3,
A zoom lens for projection, wherein the position of the seventh lens group does not change with respect to a planar image that is an object during zooming. The projection zoom lens according to any one of claims 1 to 4,
A zoom lens for projection, wherein the first lens group does not change its position with respect to a planar image during zooming. The projection zoom lens according to any one of claims 1 to 5,
The zoom lens for projection, wherein the sixth lens group includes a surface having the smallest absolute value of the radius of curvature of the refracting surface in the entire system. The zoom lens for projection according to any one of claims 1 to 6,
The focal length of the third lens group is f3, the focal length of the fourth lens group is f4, and the focal length of the fifth lens group is f5.
(1) (1 / f5)-(1 / f3)> 0
(2) (1 / f5)-(1 / f4)> 0
Projection zoom lens characterized by satisfying The zoom lens for projection according to any one of claims 1 to 7,
The third lens group and the fifth lens group are each composed of only a positive lens,
The fourth lens group includes at least one positive lens and at least one negative lens. The zoom lens for projection according to any one of claims 1 to 8,
The focal length at the telephoto end in the entire system: fT, the focal length at the wide-angle end in the entire system: fW, the distance from the optical axis to the farthest part of the planar image: Ymax, and the longest in the entire zoom range Total lens length: OAL, conditions:
(3) 5 · fT / fW <OAL / Ymax <8 · fT / fW
Projection zoom lens characterized by satisfying The projection zoom lens according to any one of claims 1 to 9,
A zoom lens for projection, wherein the third lens group comprises only one positive lens. The projection zoom lens according to any one of claims 1 to 10,
A projection zoom lens, wherein the fourth lens group has a configuration in which a positive lens and a negative lens are arranged separately or joined in order from the magnification side. The zoom lens for projection according to any one of claims 1 to 11,
5. The projection zoom lens according to claim 5, wherein the fifth lens group includes at least two positive meniscus lenses having a convex surface directed toward the enlargement side. The projection zoom lens according to any one of claims 1 to 12,
A projection zoom lens comprising a cemented lens having a cemented surface convex toward the reduction side in the sixth lens group. The projection zoom lens according to any one of claims 1 to 13,
A projection zoom lens, wherein the first lens group is formed by separately or cementing a positive lens and a negative lens. The projection zoom lens according to any one of claims 1 to 14,
A projection zoom lens, characterized in that it is a telecentric optical system in which the pupil position on the planar image side is almost infinite.   A projector apparatus equipped with the projection zoom lens according to any one of claims 1 to 15.   An imaging apparatus using the zoom lens according to any one of claims 1 to 15 for imaging.

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