JP2008304858A - Attachment lens, projection device and projection type display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an attachment lens capable of easily correcting distortion aberration and suitably used when the projection optical system of a projection device for enlarging the image of a spatial modulation element onto a screen is set as a main lens, and the projection device using the same and a projection type display device. <P>SOLUTION: The attachment lens arranged on the longer conjugate distance side of the main lens comprises a first lens having positive power and a second lens having negative power in order from the longer conjugate distance side. The attachment lens satisfies a following expression: 1.01<f_all/f_main<1.05 when the synthetic focal length of the attachment lens and the main lens is defined as f_all and the focal length of the main lens is defined as f_main. Then, the projection device using the attachment lens and the projection type display device using the projection device are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an attachment lens, a projection device, and a projection display device arranged in front of a main lens, and more specifically, when a projection optical system of a projection device that enlarges an image of a spatial modulation element on a screen is a main lens. The present invention relates to a suitable attachment lens, and a projection apparatus and a projection display apparatus using the same.

  There is a projection apparatus that uses reflective spatial modulation elements of the three primary colors of red, green, and blue. In such a projection apparatus, a prism for guiding illumination light and a color composition prism are arranged between the projection lens and the spatial modulation element. For this reason, the projection lens requires a long back focus. In addition, since the color synthesis prism has an incident angle dependency in the spectral characteristics, the projection lens must be an optical system that makes the pupil position on the short conjugate distance side far enough from the spatial modulation element, that is, telecentricity is required. It is.

  When a reflective spatial modulation element is used in a projection apparatus, a prism is required in addition to the color separation / combination prism to guide illumination light to the spatial modulation element. Therefore, a longer back focus is required for the projection lens.

  Furthermore, there is a demand for shortening the projection distance from the screen to the projection device to use in a small space, and a wide-angle zoom lens that can be used at a short projection distance is also demanded for the projection lens.

In response to the above demand, there is a configuration described in Patent Document 1, for example. The configuration described in Patent Document 1 is a so-called convex group leading four-group zoom lens, and has an advantage that long back focus and telecentricity do not change even by zooming. Further, as a compact three-group zoom lens, the present inventor has proposed a configuration described in Patent Document 2.
Japanese Patent Laid-Open No. 10-161027 JP 2004-138777 A

  The lens systems described in Patent Documents 1 and 2 do not satisfy all the requirements of having a long back focus and telecentricity and corresponding to a wide angle. Generally, when a zoom lens system having a long back focus and telecentricity is to be widened, distortion on the wide angle side becomes a problem. Therefore, conventionally, there are many designs that give priority to reducing the image forming performance at the wide-angle end and the size of the lens system closest to the incident side, and undercorrect the distortion aberration.

  However, in recent years, the specifications required for projection lenses have increased, and the required level of distortion has also improved. For this reason, the conventional wide-angle zoom lens system has been insufficiently corrected for distortion. In particular, two or more projectors make up a single screen and use it in a stack screen to obtain a brighter screen, or multiple screens that make multiple screens close together to form a large screen. Since the distortion of the screen projected by the projection lens significantly reduces the quality of the screen, correction of distortion aberration of the conventional projection lens has been insufficient.

  In view of the above problems, an object of the present invention is to provide an optical system that easily corrects distortion.

The above object is achieved by the following attachment lens. That is, the attachment lens of the present invention is an attachment lens arranged at the longer conjugate distance of the main lens, and the first lens having a positive power and the second lens having a negative power in order from the longer conjugate distance. When the combined focal length of the attachment lens and the main lens is f_all and the focal length of the main lens is f_main, the following expression is satisfied.
1.01 <f_all / f_main <1.05 (1)

  According to the present invention, an optical system such as an attachment lens that can easily correct distortion, and that is suitable when the projection optical system of a projection apparatus that enlarges an image of a spatial modulation element on a screen is used as a main lens, and its optical A projection apparatus and a projection display apparatus using the system can be provided.

(Embodiment 1)
A zoom lens system to which an attachment lens according to Embodiment 1 is added (hereinafter referred to as the entire zoom lens system) will be described with reference to the drawings. FIG. 1 is a lens arrangement diagram of the entire zoom lens system according to the first embodiment. FIG. 1A is a lens arrangement diagram at the wide-angle end of the entire zoom lens system according to Embodiment 1. FIG. FIG. 1B is a lens arrangement diagram in the intermediate focal length state of the entire zoom lens system according to the first embodiment. FIG. 1C is a lens arrangement diagram at the telephoto end of the entire zoom lens system according to Embodiment 1.

  FIG. 4 is a lens arrangement diagram of the entire zoom lens system according to the first embodiment. 4A is a lens arrangement diagram at the wide-angle end of the entire zoom lens system according to Embodiment 1. FIG. FIG. 4B is a lens arrangement diagram in the intermediate focal length state of the entire zoom lens system according to Embodiment 1.

  FIG. 6 is a lens arrangement diagram of the entire zoom lens system according to the first embodiment. FIG. 6A is a lens arrangement diagram at the wide-angle end of the entire zoom lens system according to Embodiment 1. FIG. FIG. 6B is a lens arrangement diagram in the intermediate focal length state of the entire zoom lens system according to Embodiment 1.

  FIG. 9 is a lens arrangement diagram of the entire zoom lens system according to the first embodiment. FIG. 9A is a lens arrangement diagram at the wide-angle end of the entire zoom lens system according to Embodiment 1. FIG. FIG. 9B is a lens arrangement diagram in the intermediate focal length state of the entire zoom lens system according to Embodiment 1. FIG. 9C is a lens arrangement diagram at the telephoto end of the entire zoom lens system according to Embodiment 1.

1, 4, 6, and 9 show the entire zoom lens system (attachment lens and main lens) in an infinitely focused state. In each figure, (a) shows the lens configuration at the wide angle end (shortest focal length state: focal length f _W ), and (b) shows the intermediate position (intermediate focal length state: focal length f _M = √ (f _W * f). _T )) shows a lens configuration, and FIG. 8C shows a lens configuration at the telephoto end (longest focal length state: focal length f _T ). Also, in each figure, the broken line arrows provided between FIGS. (A) and (b) are obtained by connecting the positions of the lens groups in the wide-angle end, the intermediate position, and the telephoto end in order from the top. Straight line. Furthermore, in each figure, the arrow attached to the lens group represents the focusing from the infinite focus state to the close object focus state. That is, the moving direction during focusing from the infinitely focused state to the close object focused state is shown. In the figure, an image plane S corresponds to a film or CCD in the case of an imaging system, or to an LCD that is a spatial modulation element in the case of a projection apparatus.

  The zoom lens system according to Embodiment 1 includes an attachment lens including lens elements L1 and L2 disposed on the side having the longest conjugate distance, and the remaining main lens. The attachment lens of the first embodiment includes lens elements L1 and L2. Lens elements L3 to L18 are main lenses. The glass block P arranged on the shortest conjugate distance side of the zoom lens system corresponds to a prism or the like.

  The configuration of the attachment lens is a two-lens configuration including a positive lens element L1 and a negative lens element L2 from the longer conjugate distance. The attachment lens of Embodiment 1 constitutes a teleconverter which is a kind of front converter.

  Generally, there are a front converter, a rear converter, and a close-up lens as a lens to be added to the main lens. The front converter can be placed in front of the main lens to increase or decrease the focal length. The rear converter is placed behind the main lens to increase the focal length. The close-up lens is arranged in front of the main lens to shorten the shortest shooting distance. In general, the front converter and rear converter are afocal.

  There are two types of front converters: teleconverters and wide converters. Teleconverters have the effect of increasing the focal length. The wide converter has the effect of shortening the focal length.

  In the present invention, distortion aberration can be effectively corrected by appropriately arranging an attachment lens arranged in front of the main lens, without preparing a special lens for forming a stack screen or a multi-screen.

  The attachment lens achieves its purpose with the above-described configuration, but preferably satisfies the following items in terms of optical performance.

The attachment lens is composed of a first lens having a positive power and a second lens having a negative power in order from the longest conjugate distance. The combined focal length of the attachment lens and the main lens is f_all, and the focal length of the main lens is When f_main is satisfied, the following conditional expression (1) is satisfied.
1.01 <f_all / f_main <1.05 (1)

  Conditional expression (1) represents the combined focal length of the attachment lens and the main lens with respect to the focal length of the main lens. If the lower limit of conditional expression (1) is exceeded, the effect of distortion correction will be reduced. If the upper limit of conditional expression (1) is exceeded, the combined focal length of the attachment lens and the main lens becomes long, and the angle of view changes.

The attachment lens includes a positive first meniscus lens having a convex surface facing a longer conjugate distance and a negative second meniscus lens having a convex surface facing a longer conjugate distance. It is preferable that the following conditional expression (2) is satisfied, where d1 is the center distance of the first lens and d12 is the air distance between the first lens and the second lens.
| D12 / d1 | <1 (2)

  Conditional expression (2) defines the air space between the first lens and the second lens by the space between the center planes of the first lens, and if it exceeds the upper limit, it is difficult to make it compact.

The attachment lens is composed of a positive first lens and a negative second lens in order from the longest conjugate distance. When the Abbe number of the first lens is νd1 and the Abbe number of the second lens is νd2, the following conditional expression It is preferable to satisfy (3).
12 <νd1-νd2 <24 (3)

  Conditional expression (3) defines the difference between the Abbe numbers of the first lens and the second lens. If the lower limit is exceeded, the chromatic aberration of magnification may be overcorrected. If the upper limit is exceeded, the chromatic aberration of magnification is insufficiently corrected. There is a fear.

  Examples 1-4 are shown below as specific numerical examples. In each numerical example, the unit of length in the table is “mm”, and the unit of angle of view is “°”. In each numerical example, r is a radius of curvature, d is a surface interval, nd is a refractive index with respect to the d line, and vd is an Abbe number with respect to the d line.

  FIG. 2 is a longitudinal aberration diagram of the entire zoom lens system according to Example 1 in a focused state at infinity. FIG. 3 is a longitudinal aberration diagram in which only the main lens of the zoom lens system according to Example 1 is in focus at infinity. FIG. 5 is a longitudinal aberration diagram of the entire zoom lens system according to Example 2 when the zoom lens system is in focus at infinity. FIG. 7 is a longitudinal aberration diagram of the entire zoom lens system according to Example 3 at the infinite focus state. FIG. 8 is a longitudinal aberration diagram of the zoom lens system according to Example 3 focusing on infinity only. FIG. 10 is a longitudinal aberration diagram of the entire zoom lens system according to Example 4 at the infinite focus state.

  In each longitudinal aberration diagram, (a) shows the aberration at the wide angle end, (b) shows the intermediate position, and (c) shows the aberration at the telephoto end. Each longitudinal aberration diagram shows spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)) in order from the left side. In the spherical aberration diagram, the vertical axis represents the F number (indicated by F in the figure), the solid line is the d line (d-line), the short broken line is the F line (F-line), and the long broken line is the C line (C- line). In the astigmatism diagram, the vertical axis represents the image height (indicated by H in the figure), the solid line represents the sagittal plane (indicated by s), and the broken line represents the meridional plane (indicated by m in the figure). is there. In the distortion diagram, the vertical axis represents the image height (indicated by H in the figure).

Example 1
(Table 1)
Conditional expression (1) f_all / f_main = 1.025
Conditional expression (2) | d12 / d1 | = 0.333
Conditional expression (3) νd1−νd2 = 16.5

Surface data Surface number rd nd vd
Object ∞ 2700.00000
1 136.80700 6.00000 1.48749 70.4
2 181.31000 2.00000
3 123.90000 2.00000 1.71300 53.9
4 106.00000 7.00000
5 62.84300 7.30000 1.80420 46.5
6 138.09200 0.20000
7 60.35200 1.70000 1.65844 50.9
8 27.67800 9.86500
9 128.52100 1.60000 1.49700 81.6
10 41.41100 7.62200
11 -114.05800 1.50000 1.48749 70.4
12 64.55600 Variable
13 -179.97000 10.00000 1.80610 33.3
14 -33.46100 2.00000 1.78472 25.7
15 -73.69700 5.20900
16 52.22000 4.77500 1.83400 37.3
17 228.72200 Variable
18 (Aperture) 97.42500 4.28200 1.48749 70.4
19 -52.63200 1.20000 1.84666 23.8
20 -69.44400 Variable
21 36.43700 4.75000 1.49700 81.6
22 -43.28000 1.00000 1.58913 61.3
23 35.82600 0.27600
24 42.30200 1.00000 1.83400 37.3
25 28.90400 11.89000
26 -19.25200 1.00000 1.84666 23.8
27 159.91800 7.41800 1.58913 61.3
28 -27.34300 0.34500
29 -356.42300 6.08700 1.83400 37.3
30 -36.75200 Variable
31 53.44100 5.68200 1.83400 37.3
32 ∞ 0.86200
33 ∞ 28.00000 1.58913 61.3
34 ∞ 13.84833
Image plane ∞

Various data Zoom ratio 1.32415
Wide angle Medium telephoto Focal length 26.2943 29.8929 34.8177
F number 1.67872 1.85536 2.08642
Angle of View 28.6549 25.6956 22.4828
Image height 14.3700 14.3700 14.3700
Total lens length 200.5473 200.5154 200.4946
BF 13.84833 13.81644 13.79587
d12 20.2219 14.5611 8.8986
d17 21.9656 18.8561 14.6862
d20 0.9485 5.1995 11.6359
d30 1.0000 5.5193 8.9150
Entrance pupil position 67.0453 64.9941 62.0964
Exit pupil position -3070.5803 353.8477 172.1345
Front principal point position 93.1154 97.5124 104.5492
Rear principal point position 174.0031 170.2997 165.2392

(Example 2)
(Table 2)
Conditional expression (1) f_all / f_main = 1.025
Conditional expression (2) | d12 / d1 | = 0.833
Conditional expression (3) νd1−νd2 = 16.5

Surface data Surface number rd nd vd
Object ∞ 2700.00000
1 159.75800 6.00000 1.48749 70.4
2 211.92600 5.00000
3 121.02600 2.00000 1.71300 53.9
4 106.00000 7.00000
5 62.84300 7.30000 1.80420 46.5
6 138.09200 0.20000
7 60.35200 1.70000 1.65844 50.9
8 27.67800 9.86500
9 128.52100 1.60000 1.49700 81.6
10 41.41100 7.62200
11 -114.05800 1.50000 1.48749 70.4
12 64.55600 Variable
13 -179.97000 10.00000 1.80610 33.3
14 -33.46100 2.00000 1.78472 25.7
15 -73.69700 5.20900
16 52.22000 4.77500 1.83400 37.3
17 228.72200 Variable
18 (Aperture) 97.42500 4.28200 1.48749 70.4
19 -52.63200 1.20000 1.84666 23.8
20 -69.44400 Variable
21 36.43700 4.75000 1.49700 81.6
22 -43.28000 1.00000 1.58913 61.3
23 35.82600 0.27600
24 42.30200 1.00000 1.83400 37.3
25 28.90400 11.89000
26 -19.25200 1.00000 1.84666 23.8
27 159.91800 7.41800 1.58913 61.3
28 -27.34300 0.34500
29 -356.42300 6.08700 1.83400 37.3
30 -36.75200 Variable
31 53.44100 5.68200 1.83400 37.3
32 ∞ 0.86200
33 ∞ 28.00000 1.58913 61.3
34 ∞ 13.84764
Image plane ∞

Various data Zoom ratio 1.32416
Wide angle Medium telephoto Focal length 26.2954 29.8942 34.8193
F number 1.67871 1.85536 2.08643
Angle of View 28.6539 25.6946 22.4818
Image height 14.3700 14.3700 14.3700
Total lens length 203.5466 203.5146 203.4934
BF 13.84764 13.81556 13.79468
d12 20.2219 14.5611 8.8986
d17 21.9656 18.8561 14.6862
d20 0.9485 5.1995 11.6359
d30 1.0000 5.5193 8.9150
Entrance pupil position 70.1229 68.0715 65.1736
Exit pupil position -3070.5803 353.8477 172.1345
Front principal point position 96.1941 100.5914 107.6286
Rear principal point position 177.0016 173.2978 168.2369

(Example 3)
(Table 3)
Conditional expression (1) f_all / f_main = 1.025
Conditional expression (2) | d12 / d1 | = 0.333
Conditional expression (3) νd1−νd2 = 16.5

Surface data Surface number rd nd vd
Object ∞ 2754.70800
1 139.91200 6.00000 1.48749 70.4
2 200.26800 2.00000
3 127.74200 2.00000 1.71300 53.9
4 106.00000 7.00000
5 95.83900 8.00000 1.80420 46.5
6 256.40300 0.20000
7 52.54700 1.70000 1.69680 55.5
8 27.00000 10.17500
9 207.92100 1.60000 1.48749 70.4
10 26.94300 9.73500
11 -75.58900 1.50000 1.49700 81.6
12 75.58900 Variable
13 -336.14900 12.00000 1.80610 33.3
14 -26.05600 2.00000 1.78472 25.7
15 -84.46200 1.00000
16 77.37000 6.00000 1.71736 29.5
17 -149.08200 Variable
18 95.87600 5.65000 1.48749 70.4
19 -38.66900 1.20000 1.80610 40.7
20 -49.09800 Variable
21 (Aperture) ∞ Variable
22 -205.23000 1.50000 1.84666 23.8
23 35.96100 1.00000
24 88.60500 3.00000 1.49700 81.6
25 -50.34600 4.00000
26 -16.97200 1.00000 1.64769 33.8
27 151.12900 9.30000 1.48749 70.4
28 -22.55200 0.25000
29 197.90300 9.50000 1.48749 70.4
30 -34.34700 Variable
31 48.00000 5.90000 1.78472 25.7
32 269.99000 0.86200
33 ∞ 28.00000 1.58913 61.3
34 ∞ 14.12902
Image plane ∞

Various data Zoom ratio 1.36881
Wide-angle telephoto focal length 19.1782 26.2514
F number 1.71038 2.11256
Angle of view 33.7199 26.0203
Image height 12.8100 12.8100
Total lens length 208.3953 208.3187
BF 14.12902 14.06771
d12 17.0915 6.0000
d17 30.2318 19.5205
d20 1.5334 6.8735
d21 2.0000 10.0000
d30 1.3376 9.7850
Entrance pupil position 61.6353 60.0675
Exit pupil position -151.4871 623.9369
Front principal point position 78.5909 87.4484
Rear principal point position 189.0864 181.8226

Example 4
(Table 4)
Conditional expression (1) f_all / f_main = 1.025
Conditional expression (2) | d12 / d1 | = 0.333
Conditional expression (3) νd1−νd2 = 20.4

Surface data Surface number rd nd vd
Object ∞ 2700.00000
1 155.13500 6.00000 1.59201 67.0
2 214.27800 2.00000
3 146.44800 2.00000 1.81600 46.6
4 121.38700 7.00000
5 62.84300 7.30000 1.80420 46.5
6 138.09200 0.20000
7 60.35200 1.70000 1.65844 50.9
8 27.67800 9.86500
9 128.52100 1.60000 1.49700 81.6
10 41.41100 7.62200
11 -114.05800 1.50000 1.48749 70.4
12 64.55600 Variable
13 -179.97000 10.00000 1.80610 33.3
14 -33.46100 2.00000 1.78472 25.7
15 -73.69700 5.20900
16 52.22000 4.77500 1.83400 37.3
17 228.72200 Variable
18 (Aperture) 97.42500 4.28200 1.48749 70.4
19 -52.63200 1.20000 1.84666 23.8
20 -69.44400 Variable
21 36.43700 4.75000 1.49700 81.6
22 -43.28000 1.00000 1.58913 61.3
23 35.82600 0.27600
24 42.30200 1.00000 1.83400 37.3
25 28.90400 11.89000
26 -19.25200 1.00000 1.84666 23.8
27 159.91800 7.41800 1.58913 61.3
28 -27.34300 0.34500
29 -356.42300 6.08700 1.83400 37.3
30 -36.75200 Variable
31 53.44100 5.68200 1.83400 37.3
32 ∞ 0.86200
33 ∞ 28.00000 1.58913 61.3
34 ∞ 13.84735
Image plane ∞

Various data Zoom ratio 1.32416
Wide angle Medium telephoto Focal length 26.2947 29.8934 34.8184
F number 1.67869 1.85534 2.08642
Angle of View 28.6545 25.6952 22.4824
Image height 14.3700 14.3700 14.3700
Total lens length 200.5463 200.5142 200.4929
BF 13.84735 13.81518 13.79415
d12 20.2219 14.5611 8.8986
d17 21.9656 18.8561 14.6862
d20 0.9485 5.1995 11.6359
d30 1.0000 5.5193 8.9150
Entrance pupil position 66.7056 64.6543 61.7566
Exit pupil position -3070.5803 353.8477 172.1345
Front principal point position 92.7762 97.1733 104.2104
Rear principal point position 174.0017 170.2978 165.2367

(Embodiment 2)
FIG. 11 is an optical configuration diagram of the projection apparatus according to the second embodiment. In FIG. 11, the projection apparatus includes the entire zoom lens system A shown in the first embodiment, a spatial light modulation element B that forms an optical image, and a light source C. The plane P displayed in the figure is the focus plane P of the image projected by the projection device. According to the second embodiment, the optical image formed on the spatial light modulation element B illuminated by the light source C is enlarged and projected onto the focus plane P by the projection lens (entire zoom lens system) A. By using the entire zoom lens system described in Embodiment 1 as a projection lens, a projection apparatus capable of obtaining a screen with less distortion is realized.

(Embodiment 3)
FIG. 12 is a configuration diagram of a projection display apparatus according to the third embodiment. In FIG. 12, the projection display device includes an entire zoom lens system A and a spatial light modulation element B that forms an optical image. The spatial light modulation element B has three types of optical images of blue, green, and red, respectively. Are divided in time. The color wheel D is temporally limited to three colors of blue, green, and red by rotating the R, G, and B filters. Light from the light source C is temporally decomposed into three colors of blue, green, and red by a color wheel D that is temporally limited to three colors of blue, green, and red, and illuminates the spatial light modulator B. On the spatial light modulator B, three types of optical images of blue, green, and red are formed by being temporally divided and enlarged and projected by the projection lens (entire zoom lens system) A. By using the entire zoom lens system in which the attachment lens shown in the first embodiment is attached to the projection lens A, a projection display device that can obtain a bright image with little color blur and distortion is realized in a compact manner.

(Embodiment 4)
FIG. 13 is a configuration diagram of a rear projector according to the fourth embodiment. In FIG. 13, the rear projector includes the projection display device G shown in the third embodiment, a mirror H that bends light, a transmission screen I, and a housing J. The image projected from the projection display device G is reflected by the mirror H and formed on the transmission screen I. According to the fourth embodiment, by using the projection display apparatus shown in the third embodiment as the projection display apparatus G, a high-definition rear projector is realized in a compact manner.

(Embodiment 5)
FIG. 14 is a configuration diagram of a multivision system according to the fifth embodiment. In FIG. 14, the multivision system includes the projection display device G, the transmissive screen I, the housing K, and the image dividing circuit L that divides the image shown in the third embodiment. The image signal is processed and divided by the image dividing circuit L and sent to a plurality of projection display devices G. An image projected from the projection display device G is formed on the transmission screen I. According to the fifth embodiment as described above, by using the projection display device shown in the third embodiment as the projection display device G, the multi-vision system having no sense of incongruity without shifting the joint of the image is made compact. Realized.

  The attachment lens according to the present invention is suitable for a projection apparatus, particularly a projection display apparatus that performs display such as stack display and multi-display.

Lens arrangement diagram showing the infinitely focused state of the entire zoom lens system according to Embodiment 1 (Example 1) Longitudinal aberration diagram of the entire zoom lens system according to Example 1 in an infinite focus state Fig. 5 is a longitudinal aberration diagram of the zoom lens system according to Example 1 in which only the main lens is in focus at infinity. Lens arrangement diagram showing the infinitely focused state of the entire zoom lens system according to Embodiment 1 (Example 2) Longitudinal aberration diagram of the entire zoom lens system according to Example 2 in a focused state at infinity Lens arrangement diagram showing an infinitely focused state of the entire zoom lens system according to Embodiment 1 (Example 3) Longitudinal aberration diagram of the entire zoom lens system according to Example 3 in an infinite focus state Fig. 5 is a longitudinal aberration diagram when the main lens of the zoom lens system according to Example 3 is in focus at infinity. Lens arrangement diagram showing an infinitely focused state of the entire zoom lens system according to Embodiment 1 (Example 4) Longitudinal aberration diagram of the entire zoom lens system according to Example 4 in an infinite focus state Optical configuration diagram of a projection apparatus according to Embodiment 2 Configuration of a projection display apparatus according to Embodiment 3 Configuration diagram of rear projector according to Embodiment 4 Configuration diagram of multi-vision system according to Embodiment 5

Explanation of symbols

L1 Positive lens element L2 Negative lens element A Aperture

Claims (7)

An attachment lens arranged on the longer conjugate distance of the main lens,
A first lens having a positive power and a second lens having a negative power in order from the longest conjugate distance, and the combined focal length of the attachment lens and the main lens is f_all, and the focal length of the main lens is f_main. Attachment lens satisfying the following formula:
1.01 <f_all / f_main <1.05 (1) The first lens has a positive meniscus shape with a convex surface facing a longer conjugate distance, and the second lens has a negative meniscus shape with a convex surface facing a longer conjugate distance,
The attachment lens according to claim 1, wherein when the thickness along the optical axis of the first lens is d1, and the air gap between the first lens and the second lens is d12, the following expression is satisfied:
| D12 / d1 | <1 (2) The attachment lens according to claim 1, wherein when the Abbe number of the first lens is νd1 and the Abbe number of the second lens is νd2, the following expression is satisfied:
12 <νd1-νd2 <24 (3) A light source, a spatial light modulation element that is illuminated with light emitted from the light source and forms an optical image, and a projection lens that projects the optical image on the spatial light modulation element,
4. The projection apparatus, wherein the projection lens includes the main lens and the attachment lens according to claim 1. Between the light source and the spatial light modulation element, provided with means for temporally limiting the light from the light source to three colors of blue, green, red,
The projection apparatus according to claim 4, wherein the spatial light modulation element forms an optical image corresponding to three colors of blue, green, and red that is illuminated with light emitted from the light source and changes with time.   A projection display device comprising: the projection device according to claim 5; a mirror that bends image light from the projection device; and a transmission screen that receives the image light and projects it as an optical image.   A plurality of projection devices according to claim 5, an image dividing circuit for dividing an image signal into divided images corresponding to the plurality of projection devices, and image light from the plurality of projection devices is received and synthesized as an optical image. A projection display device comprising a screen for projecting.