Projection lens structure

Abstract

A projection lens structure mainly includes a first group of lenses with a negative dioptric value, a second group of lenses with a positive dioptric value, a third group of lenses with a positive dioptric value and a fourth group of lenses with a negative dioptric value. The first group of lenses further includes at least a first lens and a second lens, of which the first lens ha a plastic aspheric lens in a meniscus shape with a focal length between −25˜−80 mm. The second group of lenses further includes at least a third lens. The third group of lenses further includes at least a first doublet with a focal length between 25˜80 mm. The fourth group of length further includes at least a group of doublets, a fourth lens and a fifth lens.

Claims

1. A projection lens structure, comprising: a first group of lenses including at least a first lens and a second lens with a negative dioptric value, said first lens being a plastic aspheric lens in a meniscus shape with a focal length between −25˜−80 mm; a second group of lenses with a positive dioptric value, including at least a third lens; a third group of lenses with a positive dioptric value, including at least a first doublet with a focal length between 25˜80 mm; and a fourth group of lenses with a negative dioptric value, including at least a group of doublets, a fourth lens and a fifth lens.

2. The projection lens structure as claimed in claim 1, wherein the fourth lens is a positive glass lens; the fifth lens is a positive glass lens; and the group of doublets includes at least one positive glass lens.

3. The projection lens structure as claimed in claim 1, wherein the group of doublets includes at least a second doublet and a third doublet, both doublets including at least one positive glass lens.

4. The projection lens structure as claimed in claim 3, wherein the third doublet has a focal length between −30˜−60 mm.

5. The projection lens structure as claimed in claim 1, wherein the group of doublets includes at least one triplet lens with a focal length between −30˜−40 mm and including at least two negative glass lenses.

6. The projection lens structure as claimed in claim 1, wherein the first group of lenses has an abbe number between 90-140; the second group of lenses has an abbe number between 25-55; the third group of lenses has an abbe number between 50-80; and the fourth group of lenses has an abbe number between 250-330 in total.

7. The projection lens structure as claimed in claim 1, wherein the structure further includes an aperture stop disposed between the third and the fourth group of lenses with an f-number between 1.6˜2.0.

8. The projection lens structure as claimed in claim 1, wherein the structure conforms to the following prerequisite factors: $-2.0>\frac{\mathrm{fla}}{fw}<-1.1;$ $2.0>\frac{f4}{fw}<3.2;$ $1.48<\frac{Bf}{fw}<1\mathrm{.71};$ where fla is an effective focal length of the first group of lenses; fw is an focal length of the projection system structure under wide-angle mode; f4 is an effective focal length of the fourth group of lenses; and Bf is an air-conversion length of back-focus of the projection system structure.

9. The projection lens structure as claimed in claim 1, wherein the projection system structure is convertible between wide-angle mode and telescope mode and the first group of lenses arranged as the focusing lenses for the groups of lenses to operate focusing by a digital mirror device, when in wide-angle mode, the first and second groups of lenses being far from the digital mirror device and the third and fourth groups of lenses being close to the digital mirror device, when in telescope mode, the first and second groups of lenses being close to the digital mirror device and the third and fourth groups of lenses being far from the digital mirror device.

10. The projection lens structure as claimed in claim 1, wherein the projection system structure has a zoom ratio of 1.0×-1.5×.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A is a schematic diagram illustrating lenses arrangement of the present invention under wide-angle mode in a first embodiment;

(2) FIG. 1B is a transverse ray fan plot with an image height of 0.0000 mm under wide-angle mode according to the first embodiment of the present invention;

(3) FIG. 1C is a transverse ray fan plot with an image height of 0.8480 mm under wide-angle mode according to the first embodiment of the present invention;

(4) FIG. 1D is a transverse ray fan plot with an image height of 2.5430 mm under wide-angle mode according to the first embodiment of the present invention;

(5) FIG. 1E is a transverse ray fan plot with an image height of 4.2380 mm under wide-angle mode according to the first embodiment of the present invention;

(6) FIG. 1F is a transverse ray fan plot with an image height of 8.4770 mm under wide-angle mode according to the first embodiment of the present invention;

(7) FIG. 1G is a field curvature diagram of the present invention under wide-angle mode in the first embodiment;

(8) FIG. 1H is a distortion diagram of the present invention under wide-angle mode in the first embodiment;

(9) FIG. 2A is a schematic diagram illustrating lenses arrangement of the present invention under telescope mode in a first embodiment;

(10) FIG. 2B is a transverse ray fan plot with an image height of 0.0000 mm under telescope mode according to the first embodiment of the present invention;

(11) FIG. 2C is a transverse ray fan plot with an image height of 0.8480 mm under telescope mode according to the first embodiment of the present invention;

(12) FIG. 2D is a transverse ray fan plot with an image height of 2.5430 mm under telescope mode according to the first embodiment of the present invention;

(13) FIG. 2E is a transverse ray fan plot with an image height of 4.2380 mm under telescope mode according to the first embodiment of the present invention;

(14) FIG. 2F is a transverse ray fan plot with an image height of 8.4770 mm under telescope mode according to the first embodiment of the present invention;

(15) FIG. 2G is a field curvature diagram of the present invention under telescope mode in the first embodiment;

(16) FIG. 2H is a distortion diagram of the present invention under telescope mode in the first embodiment;

(17) FIG. 3A is a schematic diagram illustrating lenses arrangement of the present invention under wide-angle mode in a second embodiment;

(18) FIG. 3B is a transverse ray fan plot with an image height of 0.0000 mm under wide-angle mode according to the second embodiment of the present invention;

(19) FIG. 3C is a transverse ray fan plot with an image height of 1.5610 mm under wide-angle mode according to the second embodiment of the present invention;

(20) FIG. 3D is a transverse ray fan plot with an image height of 3.9010 mm under wide-angle mode according to the second embodiment of the present invention;

(21) FIG. 3E is a transverse ray fan plot with an image height of 5.4620 mm under wide-angle mode according to the second embodiment of the present invention;

(22) FIG. 3F is a transverse ray fan plot with an image height of 7.8030 mm under wide-angle mode according to the second embodiment of the present invention;

(23) FIG. 3G is a field curvature diagram of the present invention under wide-angle mode in the second embodiment;

(24) FIG. 3H is a distortion diagram of the present invention under wide-angle mode in the second embodiment;

(25) FIG. 4A is a schematic diagram illustrating lenses arrangement of the present invention under telescope mode in a second embodiment;

(26) FIG. 4B is a transverse ray fan plot with an image height of 0.0000 mm under telescope mode according to the second embodiment of the present invention;

(27) FIG. 4C is a transverse ray fan plot with an image height of 1.5610 mm under telescope mode according to the second embodiment of the present invention;

(28) FIG. 4D is a transverse ray fan plot with an image height of 3.9010 mm under telescope mode according to the second embodiment of the present invention;

(29) FIG. 4E is a transverse ray fan plot with an image height of 5.4620 mm under telescope mode according to the second embodiment of the present invention;

(30) FIG. 4F is a transverse ray fan plot with an image height of 7.8030 mm under telescope mode according to the second embodiment of the present invention;

(31) FIG. 4G is a field curvature diagram of the present invention under telescope mode in the second embodiment; and

(32) FIG. 4H is a distortion diagram of the present invention under telescope mode in the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(33) Referring to FIGS. 1A-4H, the present invention is a projection lens structure 50A, 50B, mainly comprising a first group of lenses 10, a second group of lenses 20, a third group of lenses 30, a fourth group of lenses 40 and an aperture stop S.

(34) The first group of lenses 10 includes at least a first lens L.sub.1 and a second lens L.sub.2 with a negative dioptric value. The first lens L.sub.1 is a plastic aspheric lens in a meniscus shape with a focal length between −25˜−80 mm. The second group of lenses 20 has a positive dioptric value and includes at least a third lens L.sub.3. The third group of lenses 30 has a positive dioptric value and includes at least a first doublet C.sub.1 with a focal length between 25˜80 mm. The fourth group of lenses 40 has a negative dioptric value and includes at least a group of doublets C, a fourth lens L.sub.4 and a fifth lens L.sub.5.

(35) In the embodiment, the fourth lens L.sub.4 is a positive glass lens; the fifth lens L.sub.5 is a positive glass lens; and the group of doublets C includes at least one positive glass lens. The first group of lenses 10 has an abbe number between 90-140; the second group of lenses 20 has an abbe number between 25-55; the third group of lenses 30 has an abbe number between 50-80; and the fourth group of lenses 40 has an abbe number between 250-330 in total. The aperture stop S has an f-number between 1.6˜2.0 and is disposed between the third and the fourth group of lenses 30, 40.

(36) Furthermore, the projection lens structure 50A, 50B has the first lens L.sub.1, the second lens L.sub.2, the third lens L.sub.3, the first doublet C.sub.1, the group of doublets C, the fourth lens L.sub.4 and the fifth lens L.sub.5 to be operated by the first, second, third and fourth group of lenses 10, 20, 30, 40 for zooming and focusing. The prerequisite factors of the lenses and the projection lens structure 50A, 50B are as following:

(37) $-2.0>\frac{\mathrm{fla}}{fw}<-1.1;$$2.0>\frac{f4}{fw}<3.2;$$1.48<\frac{Bf}{fw}<1\mathrm{.71};$

(38) where

(39) fla is an effective focal length of the first group of lenses 10;

(40) fw is an focal length of the projection system structure 50A, 50B under a wide-angle mode;

(41) f4 is an effective focal length of the fourth group of lenses 40; and

(42) Bf is an air-conversion length of back-focus of the projection system structure. But the present invention is not limited to such application.

(43) When the present invention is operated, the structure is converted between a wide-angle mode and a telescope mode and the first group of lenses 10 is arranged as the focusing lenses for the groups of lenses to operate focusing by a digital mirror device DMD. When in the wide-angle mode, the first and second groups of lenses 10, 20 are far from the digital mirror device DMD and the third and fourth groups of lenses 30, 40 are close to the digital mirror device DMD. When in the telescope mode, the first and second groups of lenses 10, 20 are close to the digital mirror device DMD and the third and fourth groups of lenses 30, 40 are far from the digital mirror device DMD. The structure further has a zoom ratio of 1.0×-1.5×. There are two embodiments illustrated here, and both of the embodiments include the features above, but the present invention is not limited to such application.

(44) Referring to FIGS. 1A-2H, in the first embodiment of the present invention, both the second doublet C.sub.2 and the third doublet C.sub.3 of the group of doublets C include at least one negative glass lens. Further with reference to the following chart, the third doublet C.sub.3 has a focal length between −30˜−60 mm.

(45) TABLE-US-00001 Lenses Effective focal length (mm) L.sub.1 −55.25 L.sub.2 −31.74 L.sub.3 −60.14 C.sub.1 50.25 C.sub.2 −836.69 C.sub.3 −42.70 L.sub.4 35.43 L.sub.5 53.97

(46) Moreover, the first lens L.sub.1, the second lens L.sub.2, the third lens L.sub.3, a sixth lens C.sub.11 of the first doublet C.sub.1, a seventh lens C.sub.12 of the first doublet C.sub.1, an eighth lens C.sub.21 of the second doublet C.sub.2, a ninth lens C.sub.22 of the second doublet C.sub.2, a tenth lens C.sub.31 of the third doublet C.sub.3, an eleventh lens C.sub.32 of the third doublet C.sub.3, the fourth lens L.sub.4 and the fifth lens L.sub.5 each has a refraction rate and an abbe number, and an abbe number of each group of the lenses 10, 20, 30, 40 is further calculated according to the following specification:

(47) TABLE-US-00002 Lenses Refraction rate Abbe number L.sub.1 1.52 55.95 L.sub.2 1.58 61.24 10 — 117.2 L.sub.3 1.77 49.61 20 — 49.6 C.sub.11 1.62 35.71 C.sub.12 1.81 41.02 30 — 76.7 C.sub.21 1.71 29.51 C.sub.22 1.49 81.59 C.sub.31 1.66 33.05 C.sub.32 1.49 81.59 L.sub.4 1.49 81.59 L.sub.5 1.92 18.89 40 — 326.2

(48) In the table below, the radius, thickness, refraction rate and abbe number of each surface of the lenses are illustrated. In the table, the 1R.sub.1 is the projecting surface of the first lens L.sub.1 and the 1R.sub.2 is the image inputting surface of the first lens L.sub.1; the 2R.sub.1 is the projecting surface of the second lens L.sub.2 and the 2R.sub.2 is the image inputting surface of the second lens L.sub.2; the 3R.sub.1 is the projecting surface of the third lens L.sub.3 and the 3R.sub.2 is the image inputting surface of the third lens L.sub.3; the 4R.sub.1 is the projecting surface of the first doublet C.sub.1; the 5R.sub.1 is the projecting surface of the first doublet C.sub.1; the 5R.sub.2 is the image inputting surface of the first doublet C.sub.1; the 6R.sub.1 is the projecting surface of the second doublet C.sub.2; the 7R.sub.1 is the projecting surface of the second doublet C.sub.2; the 7R.sub.2 is the image inputting surface of the second doublet C.sub.2; the 8R.sub.1 is the projecting surface of the third doublet C.sub.3; the 9R.sub.1 is the projecting surface of the third doublet C.sub.3; the 9R.sub.2 is the image inputting surface of the third doublet C.sub.3; the 10R.sub.1 is the projecting surface of the fourth lens L.sub.4; the 10R.sub.2 is the image inputting surface of the fourth lens L.sub.4; 11R.sub.1 is the projecting surface of the fifth lens L.sub.5 and 11R.sub.2 is the image inputting surface of the fifth lens L.sub.5.

(49) TABLE-US-00003 Surface Radius Thickness Refraction Abbe no. (mm) (mm) rate number 1R.sub.1 14.04 3.00 1.52 55.95 1R.sub.2 8.78 — — — 2R.sub.1 −81.18 1.30 1.58 61.24 2R.sub.2 24.60 — — — 3R.sub.1 115.94 4.05 1.77 49.61 3R.sub.2 −77.14 — — — 4R.sub.1 40.27 1.10 1.62 35.71 5R.sub.1 22.43 4.39 1.81 41.02 5R.sub.2 201.68 — — — S Infinity — — — 6R.sub.1 Infinity 1.00 1.71 29.51 7R.sub.1 13.34 3.97 1.49 81.59 7R.sub.2 −33.12 — — — 8R.sub.1 −15.00 1.00 1.66 33.05 9R.sub.1 37.07 4.48 1.49 81.59 9R.sub.2 −22.33 — — — 10R.sub.1 44.76 5.91 1.49 81.59 10R.sub.2 −27.92 — — — 11R.sub.1 50.62 4.53 1.92 18.89 11R.sub.2 Infinity — — —

(50) In addition, the following table displays the radius, the conic value and order aspheric coefficients of the projecting surface 1R.sub.1 and the image inputting surface 1R.sub.2 of the second lens L.sub.1 as a plastic aspheric lens.

(51) TABLE-US-00004 Aspheric lens 1R.sub.1 1R.sub.2 Radius 14.04  8.78 Conic −2.22 −1.48 4th −3.00E−05 −6.00E−06 6th  1.10E−07  1.70E−07 8th −5.14E−11 −1.05E−09 10th −4.50E−13  9.20E−12 12th  9.20E−16 −4.10E−14 14th −3.60E−19  6.70E−17

(52) Furthermore, when the projection system structure 50A switches between the wide-angle mode and the telescope mode, a first distance D.sub.1 is arranged between the first and second group of lenses 10, 20, a second distance D.sub.2 is arranged between the second and the third group of lenses 20, 30, a third distance D.sub.3 is arranged between the third and the fourth group of lenses 30, 40 and a fourth distance D.sub.4 is arranged between the fourth group of lenses 40 and the digital mirror device DMD. The distances under different modes are shown in the following table.

(53) TABLE-US-00005 Distance (mm) Wide-angle mode 1.1x Telescope mode D.sub.1 24.26 21.31 19.25 D.sub.2 13.47 7.07 1.66 D.sub.3 6.93 8.83 10.72 D.sub.4 18.82 20.09 21.29

(54) The projection system structure 50A can be operated for zooming to 1.2×, and the effective focal lengths of the groups of the lenses 10, 20, 30, 40 conforms to the prerequisite factors:

(55) $-2.0>\frac{\mathrm{fla}}{fw}<-1.1;$$2.0>\frac{f4}{fw}<3.2;$$1.48<\frac{Bf}{fw}<1\mathrm{.71};$

(56) where

(57) fla is an effective focal length of the first group of lenses;

(58) fw is an focal length of the projection system structure under wide-angle mode;

(59) f4 is an effective focal length of the fourth group of lenses; and

(60) Bf is an air-conversion length of back-focus of the projection system structure. In the following table, the effective focal lengths of the groups of the lenses 10, 20, 30, 40 and of the projection system structure 50A under the wide-angle mode are shown.

(61) TABLE-US-00006 Groups of lenses Wide-angle mode 1.1x 1.2x 10 −18.28 −18.28 −18.28 20 60.51 60.51 60.51 30 50.6 50.6 50.6 40 28.71 28.71 28.71 50A 12.61 13.87 15.12 zooming ratio — 1.1 1.2

(62) As disclosed above, the projection lens 50A under the wide-angle mode has a first wavelength λ.sub.1 set as 0.486 um, a second wavelength λ.sub.2 set as 0.588 um and a third wavelength λ.sub.3 set as 0.656 um; thereby it is able to simulate different transverse ray fan plots as shown in FIGS. 1B-1F and to display images with respective image heights of 0.0000 mm, 0.8480 mm, 2.5430 mm, 4.2380 mm and 8.477 mm on the image IMA. The transverse aberration of a Y-axis is represented by ey. The pupil height of the Y-axis is represented by py. The transverse aberration of an X-axis is represented by ex. The pupil height of the X-axis is represented by px. The maximum of the transverse aberration of the X-axis and the Y-axis is ±20.000 um and the pupil heights of the X-axis and the Y-axis are in normalized proportion; a maximum field of FIGS. 1G and 1H is 33.749°.

(63) When the projection lens 50A is under the telescope mode, it has a first wavelength λ.sub.1 set as 0.486 um, a second wavelength λ.sub.2 set as 0.588 um and a third wavelength λ.sub.3 set as 0.656 um; thereby it is able to simulate different transverse ray fan plots as shown in FIGS. 2B-2F and to display images with respective image heights of 0.0000 mm, 0.8480 mm, 2.5430 mm, 4.2380 mm and 8.477 mm on the image IMA. The transverse aberration of a Y-axis is represented by ey. The pupil height of the Y-axis is represented by py. The transverse aberration of an X-axis is represented by ex. The pupil height of the X-axis is represented by px. The maximum of the transverse aberration of the X-axis and the Y-axis is ±20.000 um and the pupil heights of the X-axis and the Y-axis are in normalized proportion; a maximum field of FIGS. 2G and 2H is 29.316°.

(64) From the data disclosed above, it is obvious that the present invention has a simple structure with low manufacturing costs but still keeps a fine quality of projection.

(65) Referring to FIGS. 3A-4H, in the second embodiment of the present invention, the group of doublets C includes at least one triplet lens which including at least two negative glass lens. Further with reference to the following chart, the triplet lens has a focal length between −30˜−40 mm.

(66) TABLE-US-00007 Lenses Effective focal length (mm) L.sub.1 −37.55 L.sub.2 −27.81 L.sub.3 49.64 C.sub.1 45.84 C −36.47 L.sub.4 32.03 L.sub.5 52.76

(67) Moreover, the first lens L.sub.1, the second lens L.sub.2, the third lens L.sub.3, the first doublet C.sub.1, a twelfth lens C.sub.01 of the group of doublets C, a thirteenth lens C.sub.02 of the group of doublets C, a fourteenth lens C.sub.03 of the group of doublets C, the fourth lens L.sub.4 and the fifth lens L.sub.5 each has a refraction rate and an abbe number, and an abbe number of each group of the lenses 10, 20, 30, 40 is further calculated according to the following specification:

(68) TABLE-US-00008 Lenses Refraction rate Abbe number L.sub.1 1.52 55.95 L.sub.2 1.64 39.67 10 — 95.6 L.sub.3 1.83 42.73 20 — 42.7 C.sub.11 1.80 24.97 C.sub.12 1.84 33.61 30 — 58.6 C.sub.01 1.75 26.42 C.sub.02 1.49 81.59 C.sub.03 1.78 39.86 L.sub.4 1.49 81.59 L.sub.5 1.85 23.77 40 — 253.2

(69) In the table below, the radius, thickness, refraction rate and abbe number of each surface of the lenses are illustrated. In the table, the 1R.sub.1 is the projecting surface of the first lens L.sub.1 and the 1R.sub.2 is the image inputting surface of the first lens L.sub.1; the 2R.sub.1 is the projecting surface of the second lens L.sub.2 and the 2R.sub.2 is the image inputting surface of the second lens L.sub.2; the 3R.sub.1 is the projecting surface of the third lens L.sub.3 and the 3R.sub.2 is the image inputting surface of the third lens L.sub.3; the 4R.sub.1 is the projecting surface of the first doublet C.sub.1; the 5R.sub.1 is the projecting surface of the first doublet C.sub.1; the 5R.sub.2 is the image inputting surface of the first doublet C.sub.1; the 6R.sub.1 is the projecting surface of the group of doublets C; the 7R.sub.1 is the projecting surface of the group of doublets C; the 8R.sub.1 is the projecting surface of the group of doublets C; the 8R.sub.2 is the image inputting surface of the group of doublets C; the 9R.sub.1 is the projecting surface of the fourth lens L.sub.4; the 9R.sub.2 is the image inputting surface of the fourth lens L.sub.4; 10R.sub.1 is the projecting surface of the fifth lens L.sub.5 and 10R.sub.2 is the image inputting surface of the fifth lens L.sub.5.

(70) TABLE-US-00009 Surface Radius Thickness Refraction Abbe no. (mm) (mm) rate number 1R.sub.1 14.47 3.00 1.52 55.95 1R.sub.2 7.75 — — — 2R.sub.1 −32.74 1.30 1.64 39.67 2R.sub.2 39.78 — — — 3R.sub.1 1167.59 5.89 1.83 42.73 3R.sub.2 −42.84 — — — 4R.sub.1 33.19 1.50 1.80 24.97 5R.sub.1 19.62 6.44 1.84 33.61 5R.sub.2 175.85 — — — S Infinity — — — 6R.sub.1 −205.62 1.00 1.75 26.42 7R.sub.1 12.09 7.38 1.49 81.59 8R.sub.1 −10.32 3.18 1.78 39.86 8R.sub.2 −35.13 — — — 9R.sub.1 62.50 6.20 1.49 81.59 9R.sub.2 −20.65 — — — 10R.sub.1 33.32 3.32 1.85 23.77 10R.sub.2 125.17 — — —

(71) In addition, the following table displays the radius, the conic value and order aspheric coefficients of the projecting surface 1R.sub.1 and the image inputting surface 1R.sub.2 of the second lens L.sub.1 as a plastic aspheric lens.

(72) TABLE-US-00010 Aspheric lens 1R.sub.1 1R.sub.2 Radius 14.47  7.75 Conic −2.87 −1.46 4th −1.80E−05 4.90E−05 6th  1.14E−07 1.25E−07 8th −1.14E−10 −5.93E−10  10th −4.09E−13 1.20E−11 12th  1.38E−15 −6.51E−14  14th −1.20E−18 1.49E−16

(73) Furthermore, when the projection system structure 50B switches between the wide-angle mode and the telescope mode, a first distance D.sub.1 is arranged between the first and second group of lenses 10, 20, a second distance D.sub.2 is arranged between the second and the third group of lenses 20, 30, a third distance D.sub.3 is arranged between the third and the fourth group of lenses 30, 40 and a fourth distance D.sub.4 is arranged between the fourth group of lenses 40 and the digital mirror device DMD. The distances under different modes are shown in the following table.

(74) TABLE-US-00011 Distance (mm) Wide-angle mode 1.1x Telescope mode D.sub.1 15.75 14.34 13.23 D.sub.2 16.58 8.06 1.50 D.sub.3 7.04 8.95 10.92 D.sub.4 17.96 18.88 19.89

(75) The projection system structure 50B can be operated for zooming to 1.2×, and the effective focal lengths of the groups of the lenses 10, 20, 30, 40 conforms to the prerequisite factors:

(76) $-2.0>\frac{\mathrm{fla}}{fw}<-1.1;$$2.0>\frac{f4}{fw}<3.2;$$1.48<\frac{Bf}{fw}<1\mathrm{.71};$

(77) where

(78) fla is an effective focal length of the first group of lenses;

(79) fw is an focal length of the projection system structure under wide-angle mode;

(80) f4 is an effective focal length of the fourth group of lenses; and

(81) Bf is an air-conversion length of back-focus of the projection system structure. In the following table, the effective focal lengths of the groups of the lenses 10, 20, 30, 40 and of the projection system structure 50A under the wide-angle mode are shown.

(82) TABLE-US-00012 Groups of lenses Wide-angle mode 1.1x 1.2x 10 −13.23 −13.23 −13.23 20 49.64 49.64 49.64 30 45.84 45.84 45.84 40 25.07 25.07 25.07 50B 10.55 10.55 12.66 zooming ratio — 1.0 1.2

(83) As disclosed above, the projection lens 50B under the wide-angle mode has a first wavelength λ.sub.1 set as 0.486 um, a second wavelength λ.sub.2 set as 0.588 um and a third wavelength λ.sub.3 set as 0.656 um; thereby it is able to simulate different transverse ray fan plots as shown in FIGS. 3B-3F and to display images with respective image heights of 0.0000 mm, 1.5610 mm, 3.9010 mm, 5.4620 mm and 7.8030 mm on the image IMA. The transverse aberration of a Y-axis is represented by ey. The pupil height of the Y-axis is represented by py. The transverse aberration of an X-axis is represented by ex. The pupil height of the X-axis is represented by px. The maximum of the transverse aberration of the X-axis and the Y-axis is ±20.000 um and the pupil heights of the X-axis and the Y-axis are in normalized proportion; a maximum field of FIGS. 3G and 3H is 36.362°.

(84) When the projection lens 50B is under the telescope mode, it has a first wavelength λ.sub.1 set as 0.486 um, a second wavelength λ.sub.2 set as 0.588 um and a third wavelength λ.sub.3 set as 0.656 um; thereby it is able to simulate different transverse ray fan plots as shown in FIGS. 4B-4F and to display images with respective image heights of 0.0000 mm, 1.5610 mm, 3.9010 mm, 5.4620 mm and 7.8030 mm on the image IMA. The transverse aberration of a Y-axis is represented by ey. The pupil height of the Y-axis is represented by py. The transverse aberration of an X-axis is represented by ex. The pupil height of the X-axis is represented by px. The maximum of the transverse aberration of the X-axis and the Y-axis is ±20.000 um and the pupil heights of the X-axis and the Y-axis are in normalized proportion; a maximum field of FIGS. 4G and 4H is 31.723°.

(85) Again, from the data disclosed above, it is obvious that the present invention has a simple structure with low manufacturing costs but still keeps a fine quality of projection.

(86) In another embodiment, the present invention can be operated for zooming to 1.3× based on the structure of the first embodiment, and the specification and data are stated in the following tables.

(87) The effective focal length of the lenses:

(88) TABLE-US-00013 Lenses Effective focal length (mm) L.sub.1 −50.14 L.sub.2 −35.95 L.sub.3 71.82 C.sub.1 44.94 C.sub.2 −1250.00 C.sub.3 −38.49 L.sub.4 34.94 L.sub.5 51.22

(89) The refraction rate and abbe number of the lenses and the abbe number of the groups of lenses 10, 20, 30, 40:

(90) TABLE-US-00014 Lenses Refraction rate Abbe number L.sub.1 1.52 55.95 L.sub.2 1.49 70.40 10 — 126.4 L.sub.3 1.80 35.00 20 — 35.0 C.sub.11 1.76 27.50 C.sub.12 1.81 33.30 30 — 60.8 C.sub.21 1.74 28.30 C.sub.22 1.49 81.59 C.sub.31 1.67 32.20 C.sub.32 1.49 81.59 L.sub.4 1.49 81.59 L.sub.5 1.92 18.89 40 — 324.2

(91) The radius, thickness, refraction rate and abbe number of each surface of the lenses:

(92) TABLE-US-00015 Surface Radius Thickness Refraction Abbe no. (mm) (mm) rate number 1R.sub.1 12.59 3.00   1.52 55.95 1R.sub.2 7.83 — — — 2R.sub.1 −72.53 1.50   1.48 70.40 2R.sub.2 23.40 — — — 3R.sub.1 115.26 3.65   1.80 34.97 3R.sub.2 −115.26 — — — 4R.sub.1 35.47 1.10000 1.75 27.50 5R.sub.1 15.80 5.14000 1.80 33.20 5R.sub.2 311.34 — — — S Infinity — — — 6R.sub.1 287.48 1.00000 1.74 28.20 7R.sub.1 13.81 3.89000 1.49 81.59 7R.sub.2 −33.81 — — — 8R.sub.1 −15.12 1.00000 1.67 32.10 9R.sub.1 28.71 4.60000 1.49 81.59 9R.sub.2 −23.30 — — — 10R.sub.1 43.35 5.40000 1.49 81.59 10R.sub.2 −27.95 — — — 11R.sub.1 48.04 4.08000 1.92 18.89 11R.sub.2 Infinity — — —

(93) The radius, conic value and order aspheric coefficient of the projecting surface 1R.sub.1 and the image inputting surface 1R.sub.2:

(94) TABLE-US-00016 Aspheric lens 1R.sub.1 1R.sub.2 Radius 12.59  7.83 Conic −2.19 −1.48 4th −2.70E−05 1.70E−05 6th  1.20E−07 1.70E−07 8th −7.25E−11 −1.01E−09  10th −4.41E−13 9.84E−12 12th  1.18E−15 −4.17E−14  14th −8.68E−19 7.45E−17

(95) The distances D.sub.1, D.sub.2, D.sub.3, D.sub.4 between the groups of the lenses 10, 20, 30, 40 under different modes:

(96) TABLE-US-00017 Distance (mm) Wide-angle mode 1.1x 1.2x Telescope mode D.sub.1 28.76 24.78 21.84 19.70 D.sub.2 11.53 8.17 4.92 1.70 D.sub.3 3.97 5.35 6.78 8.27 D.sub.4 17.96 19.13 20.26 21.33

(97) The effective focal lengths of each group of lenses at different zooming ratio:

(98) TABLE-US-00018 Groups of lenses Wide-angle mode 1.1x 1.2x 1.3x 10 −18.28 −18.28 −18.28 −18.28 20 71.82 71.82 71.82 71.82 30 44.94 44.94 44.94 44.94 40 28.64 28.64 28.64 28.64 50B 10.58 11.64 12.7 13.76 zooming ratio — 1.0 1.2 1.3

(99) In another embodiment, the present invention can be operated for zooming to 1.4× based on the structure of the first embodiment, and the specification and data are stated in the following tables.

(100) The effective focal length of the lenses:

(101) TABLE-US-00019 Lenses Effective focal length (mm) L.sub.1 −52.86 L.sub.2 −40.35 L.sub.3 64.17 C.sub.1 55.26 C.sub.2 −270.87 C.sub.3 −46.75 L.sub.4 35.35 L.sub.5 53.80

(102) The refraction rate and abbe number of the lenses and the abbe number of the groups of lenses 10, 20, 30, 40:

(103) TABLE-US-00020 Lenses Refraction rate Abbe number L.sub.1 1.52 55.95 L.sub.2 1.49 81.59 10 — 137.5 L.sub.3 1.85 30.10 20 — 30.1 C.sub.11 1.81 25.50 C.sub.12 1.85 30.10 30 — 55.6 C.sub.21 1.76 27.50 C.sub.22 1.49 81.59 C.sub.31 1.65 33.80 C.sub.32 1.49 81.59 L.sub.4 1.49 81.59 L.sub.5 1.92 18.89 40 — 325.0

(104) The radius, thickness, refraction rate and abbe number of each surface of the lenses:

(105) TABLE-US-00021 Surface Radius Thickness Refraction Abbe no. (mm) (mm) rate number 1R.sub.1 12.45 3.00 1.52 55.95 1R.sub.2 7.89 — — — 2R.sub.1 −475.04 1.50 1.49 81.59 2R.sub.2 21.04 — — — 3R.sub.1 55.12 2.60 1.86 30.10 3R.sub.2 Infinity — — — 4R.sub.1 43.38 1.00 1.81 25.50 5R.sub.1 14.98 4.75 1.85 30.10 5R.sub.2 223.62 — — — S Infinity — — — 6R.sub.1 Infinity 0.80 1.76 27.50 7R.sub.1 13.95 4.00 1.49 81.59 7R.sub.2 −34.30 — — — 8R.sub.1 −14.52 0.80 1.65 33.80 9R.sub.1 35.41 4.65 1.49 81.59 9R.sub.2 −20.87 — — — 10R.sub.1 45.20 5.82 1.49 81.59 10R.sub.2 −27.67 — — — 11R.sub.1 42.99 2.75 1.92 18.89 11R.sub.2 281.18 — — —

(106) The radius, conic value and order aspheric coefficient of the projecting surface 1R.sub.1 and the image inputting surface 1R.sub.2:

(107) TABLE-US-00022 Aspheric lens 1R.sub.1 1R.sub.2 Radius 12.45  7.89 Conic −1.74 −1.54 4th −5.70E−05 1.60E−05 6th  2.00E−07 1.60E−08 8th −2.10E−10 −2.70E−10  10th −2.72E−13 8.16E−12 12th  8.33E−16 −4.13E−14  14th −4.91E−19 6.59E−17

(108) The distances D.sub.1, D.sub.2, D.sub.3, D.sub.4 between the groups of the lenses 10, 20, 30, 40 under different modes:

(109) TABLE-US-00023 Distance (mm) Wide-angle mode 1.1x 1.2x 1.3x Telescope mode D.sub.1 39.22 33.34 28.90 25.21 22.47 D.sub.2 7.18 6.22 4.49 2.78 0.50 D.sub.3 5.43 6.59 8.01 9.45 11.08 D.sub.4 17.68 19.02 20.18 21.42 22.50

(110) The effective focal lengths of each group of lenses at different zooming ratio:

(111) TABLE-US-00024 Groups of lenses Wide-angle mode 1.1x 1.2x 1.3x 1.4x 10 −20.81 −20.81 −20.81 −20.81 −20.81 20 64.83 64.83 64.83 64.83 64.83 30 55.63 55.63 55.63 55.63 55.63 40 32.54 33.33 34.34 35.44 36.78 50B 10.56 11.62 12.67 13.73 14.78 zooming ratio — 1.0 1.2 1.3 1.4

(112) In another embodiment, the present invention can be operated for zooming to 1.5× based on the structure of the first embodiment, and the specification and data are stated in the following tables.

(113) The effective focal length of the lenses:

(114) TABLE-US-00025 Lenses Effective focal length (mm) L.sub.1 −52.61 L.sub.2 −41.32 L.sub.3 57.83 C.sub.3 54.40 C.sub.2 −317.26 C.sub.3 −48.45 L.sub.4 36.11 L.sub.5 59.02

(115) The refraction rate and abbe number of the lenses and the abbe number of the groups of lenses 10, 20, 30, 40:

(116) TABLE-US-00026 Lenses Refraction rate Abbe number L.sub.1 1.52 55.95 L.sub.2 1.49 81.59 10 — 137.5 L.sub.3 1.85 30.10 20 — 30.1 C.sub.11 1.81 25.50 C.sub.12 1.85 30.10 30 — 55.6 C.sub.21 1.76 27.50 C.sub.22 1.49 81.59 C.sub.31 1.65 33.80 C.sub.32 1.49 81.59 L.sub.4 1.49 81.59 L.sub.5 1.92 18.89 40 — 325.0

(117) The radius, thickness, refraction rate and abbe number of each surface of the lenses:

(118) TABLE-US-00027 Surface Radius Thickness Refraction Abbe no. (mm) (mm) rate number 1R.sub.1 13.21 3.00 1.52 55.95 1R.sub.2 8.23 — — — 2R.sub.1 −468.35 1.00 1.49 81.59 2R.sub.2 21.49 — — — 3R.sub.1 49.16 2.94 1.85 30.10 3R.sub.2 Infinity — — — 4R.sub.1 40.37 1.00 1.81 25.50 5R.sub.1 14.08 5.12 1.85 30.10 5R.sub.2 166.63 — — — S Infinity — — — 6R.sub.1 −596.38 1.00 1.76 27.50 7R.sub.1 13.49 4.33 1.49 81.59 7R.sub.2 −30.50 — — — 8R.sub.1 −13.92 1.00 1.65 33.80 9R.sub.1 42.44 5.01 1.49 81.59 9R.sub.2 −20.12 — — — 10R.sub.1 49.27 5.58 1.49 81.59 10R.sub.2 −27.16 — — — 11R.sub.1 43.12 3.02 1.92 18.89 11R.sub.2 200.15 — — —

(119) The radius, conic value and order aspheric coefficient of the projecting surface 1R.sub.1 and the image inputting surface 1R.sub.2:

(120) TABLE-US-00028 Aspheric lens 1R.sub.1 1R.sub.2 Radius 13.21  8.23 Conic −1.72 −1.55 4th −5.70E−05 1.70E−05 6th  2.04E−07 2.29E−08 8th −2.13E−10 −2.55E−10  10th −2.73E−13 8.19E−12 12th  8.28E−16 −4.12E−14  14th −5.04E−19 6.47E−17

(121) The distances D.sub.1, D.sub.2, D.sub.3, D.sub.4 between the groups of the lenses 10, 20, 30, 40 under different modes:

(122) TABLE-US-00029 Distance Wide-angle Telescope (mm) mode 1.1x 1.2x 1.3x 1.4x mode D.sub.1 37.48 31.64 27.02 23.39 20.57 18.41 D.sub.2 8.85 8.20 6.91 5.16 3.00 0.53 D.sub.3 4.26 5.32 6.55 7.92 9.39 10.94 D.sub.4 17.98 19.28 20.51 21.65 22.70 23.68

(123) The effective focal lengths of each group of lenses at different zooming ratio:

(124) TABLE-US-00030 Groups of Wide-angle lenses mode 1.1x 1.2x 1.3x 1.4x 1.5x 10 −20.83 −20.83 −20.83 −20.83 −20.83 −20.83 20 57.83 57.83 57.83 57.83 57.83 57.83 30 54.4 54.4 54.4 54.4 54.4 54.4 40 28.56 28.56 28.56 28.56 28.56 28.56 50B 10.56 11.62 12.68 13.73 14.79 15.84 zooming — 1.0 1.2 1.3 1.4 1.5 ratio

(125) Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except by the appended claims.