PROJECTION OPTICAL SYSTEM WITH A CONCAVE REFLECTOR IN THE PROJECTION LENS

BACKGROUND OF THE INVENTION
1. Field of the Invention

The present invention relates to a projection optical system with a concave reflector in the projection lens, particularly to one that has an image source, a lens group, an aperture, a reflector, an image, a first quadrant, a second quadrant, a third quadrant and a fourth quadrant of rectangular coordinates.

2. Description of the Related Art

Projectors have been innovated with latest technology for the past years, ranging from projectors with normal focal lengths to ones with short focal lengths. They can be applied in many aspects like multimedia presentations, television projection, family cinemas, teleconferences, etc. In recent years, projectors with short focal lengths are mainly applied in educational fields and are favorable in small families.

In view of the quality of the projected images, the longer the focal lengths are, the narrower the angle of the field of view the projectors have, and as the focal lengths become shorter, the distortion of the images gets worse. So it is impossible to guarantee the quality of the images with the focal lengths reduced. Therefore, it is desirable to make an arrangement of the structures of the projectors to achieve greater efficiency in projections while ensuring the quality of the projected images.

U.S. Pat. No. 8,054,556 disclosed a lens adapted to image a first image plane at a reduced side onto a magnified side is provided. The lens has an optical axis. The lens includes a lens group and a concave reflective mirror. The lens group is disposed in the light path between the reduced side and the magnified side. The concave reflective mirror is disposed in the light path between the lens group and the magnified side. The offset of the first image plane with respect to the optical axis is greater than 100%. The throw ratio of the lens is less than 0.3.

US Pub. No.2019/0285972A1 disclosed a first optical group that forms an intermediate image and a second optical group that enlarges and projects the intermediate image formed by the first optical group satisfy a variety of conditions. Therefore, the overall length of the entire lens system of the projection system is reduced in a linear arrangement, or the distance between the first optical group and the second optical group is increased and an optical path deflector that deflects the optical path is disposed at the middle of the optical path between the first and second optical groups to fold the optical path.

SUMMARY OF THE INVENTION

A primary objective of the present invention is to provide a projection optical system with a concave reflector in the projection lens which has an image source, a lens group, an aperture, a reflector, an image, a first quadrant, a second quadrant, a third quadrant and a fourth quadrant of rectangular coordinates that make the image source lead the optical path effectively and meanwhile provide images with better quality.

Another objective of the present invention is to provide a projection optical system that has a front group lens and a rear group lens operated correspondingly to enhance quality of the images and reduce the manufacture cost.

Yet another objective of the present invention is to provide a projection optical system that make the width of the image and the project distance of the image operated correspondingly to enhance quality of the images and make the project ratio smaller.

To achieve the objects mentioned above, the present invention comprises an image source; a lens group arranged at the lateral side of the image source; a reflector positioned at said lateral side of the lens group; an image, the lens group and the reflector form multiple optical paths between the image and image source, each optical path has a chief ray and a marginal ray; and an aperture arranged inside the lens group and the center of the aperture is defined as an origin, define the axial direction as X axis and the radial direction as Y axis to form a rectangular coordinate system, the rectangular coordinate system has a first quadrant, a second quadrant, a third quadrant, a fourth quadrant, the image source and the image located in the same quadrant, and the projection optical system has an optical axis which coincided with the X axis making the chief ray of one of the optical paths forms a chief ray of a paraxial image height at the part where image source be near to the optical axis, the chief ray of another one of the optical paths forms a marginal ray of an off-axis image height at the part where image source be far from the optical axis; wherein said projection optical system complies below features: a). 2.2<F1/F2<3.0, wherein F1 is the focal length of the reflector, and F2 is the focal length of the lens group; b). 8<IMH/TR/Fno<19, wherein IMH is the maximum image height, TR is the throw ratio, and Fno is the F-number (the ratio of the number of focal lengths to the number of apertures); c). 5<IMH*T1/T2<8, wherein IMH is the maximum image height, T1 is the distance from the reflector to the lens group, and T2 is the total length of the lens group;

Whereby when the image source and the image are located in the second quadrant and the reflector is located in the fourth quadrant, the chief ray of the paraxial image height intersects with the chief ray of the off-axis image height intersect, then sequentially forming a first point and a second point, the first point located at the origin and the second point is located in the first quadrant, and the chef ray of the optical path intersects with the marginal ray of the optical path, and sequentially forming a third point and a fourth point, the third point located at the fourth quadrant and the fourth point is located in the second quadrant.

Furthermore, the lens group can be divided into a front group lens and a rear group lens, the front group lens is close to the reflector side, and the rear group lens is close to the image source side.

Also, the front group lens includes at least two aspheric lens, and at least one of the aspheric lens is a negative lens.

Also, the rear group lens includes at least two doublet and an aspheric lens, the Nd of the last lens is 1.8-2.05 and the Abbe number of the last lens of the rear group lens is 17-24 and is close to the image source side.

Also, the width of the image is set as W and the project distance from the reflector to the image is set as T, and conforms to the conditional formula of the projection ratio of the projection optical system: 0.16<T/W<0.3.

Also, the F value of the projection optical system is 1.6-3.2.

Also, the displacement of the center point of the image source corresponding to the optical axis is define as d, and short side of the image source is defined as h, and fits the condition: 130%<2d/h>160%.

With the feature disclosed above, the present invention uses the image source, the lens group, the aperture, the reflector, the image, operated correspondingly with the first quadrant, the second quadrant, the third quadrant and the fourth quadrant of rectangular coordinates, and the front group lens and the rear group lens operated correspondingly, and the width of the image and the project distance of the image operated correspondingly to make the image source lead the optical path effectively, reduce the manufacture cost, make the project ratio smaller, and make the F value of the projection optical system smaller to be able to install with large aperture so as to enhance quality of the images.

Also, the focal length, maximum image height, throw ratio, F-number (Fno) and other numerical values of the present invention are designed to complement each other and achieve the best optical performance. Compared with the lens patent of the prior art, the projection optical system of the present invention not only has differences, but also can take into account the image quality when the projection distance is shortened, so that the projection configuration can be adjusted to the optimum, so as to obtain a good optical effect; Wherein, when 2.2<F1/F2<3.0, wherein F1 is the focal length of the reflector, and F2 is the focal length of the lens group, it will achieve optimizing optical performance for various aberrations and dimensions; when 8<IMH/TR/Fno<19, it will achieve optimizing the optimal optical performance of resolution, tolerance sensitivity and cost performance can be achieved; when 5<IMH*T1/T2<8, the optimal optical performance of resolving power and optical path interference allowance will be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram illustrating lenses arrangement of the first embodiment the present invention;

FIG. 1B is a schematic diagram illustrating a travel path of optical path of the first embodiment the present invention;

FIG. 1C is a schematic diagram illustrating the optical path of maxima image height which divided into ten equal of the first embodiment;

FIG. 1D is a schematic diagram illustrating the image of the first embodiment the present invention;

FIG. 1E is the zoom in of the 1E in the FIG. 1D;

FIG. 1F is the zoom in of the 1F in the FIG. 1D;

FIG. 1G is a ray fan plot showing an image height of 0.5830 mm of the image source of the first embodiment of the present invention;

FIG. 1H is a ray fan plot showing an image height of 0.8710 mm of the image source of the first embodiment of the present invention;

FIG. 1I is a ray fan plot showing an image height of 1.7420 mm of the image source of the first embodiment of the present invention;

FIG. 1J is a ray fan plot showing an image height of 2.6130 mm of the image source of the first embodiment of the present invention;

FIG. 1K is a ray fan plot showing an image height of 3.4840 mm of the image source of the first embodiment of the present invention;

FIG. 1L is a ray fan plot showing an image height of 4.3550 mm of the image source of the first embodiment of the present invention;

FIG. 1M is a graph illustrating the field curvature of the first embodiment;

FIG. 1N is a graph illustrating the distortion of the first embodiment;

FIG. 1O is a graph illustrating the lateral color aberration of the first embodiment;

FIG. 1P is a graph illustrating the vertical aberration of the first embodiment;

FIG. 1Q is schematic diagram illustrating the optical elements of the first embodiment;

FIG. 2A is a schematic diagram illustrating lenses arrangement of the second embodiment the present invention;

FIG. 2B is a schematic diagram illustrating a travel path of optical path of the second embodiment the present invention;

FIG. 2C is a schematic diagram illustrating the optical path of maxima image height which divided into ten equal of the second embodiment;

FIG. 3A is a schematic diagram illustrating lenses arrangement of the third embodiment the present invention;

FIG. 3B is a schematic diagram illustrating a travel path of optical path of the third embodiment the present invention;

FIG. 3C is a schematic diagram illustrating the optical path of maxima image height which divided into ten equal of the third embodiment;

FIG. 4A is a schematic diagram illustrating lenses arrangement of the fourth embodiment the present invention;

FIG. 4B is a schematic diagram illustrating a travel path of optical path of the fourth embodiment the present invention;

FIG. 4C is a schematic diagram illustrating the optical path of maxima image height which divided into ten equal of the fourth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1A-1Q, a projection optical system with a concave reflector in the projection lens 60A of the first embodiment of the present invention mainly comprises a projection optical system image source IMA, in this embodiment, the image source IMA can be coordinate with a transmissive smooth picture actuator 62, a prism 63, a cover glass 64, but the present invention is not limited to such application.

A lens group 10 arranged at the lateral side of the image source IMA; a reflector 20 arranged at the lateral side of the lens group 10; an image 30, the lens group 10 and the reflector 20 form multiple optical paths A between the image 30 and image source IMA, each optical path A has a chief ray A₁and a marginal ray A₂.

Moreover, the lens group 10 can be divided into a front group lens G₁and a rear group lens G₂, the front group lens G₁is close to the reflector 20 side, and the rear group lens G₂is close to the image source side IMA.

Also, the front group lens G₁includes at least two aspheric lens, and at least one of the aspheric lens is a negative lens; the rear group lens G₂includes at least two doublet and an aspheric lens; the Nd of the last lens is 1.8-2.05 and the Abbe number of the last lens of the rear group lens G₂is 17-24 and is close to the image source side, but the present invention is not limited to such application.

Referring to the FIG. 1A-1C, Table 1 and Table 2, the projection optical system 60A of the first embodiment has the front group lens G₁includes a first lens L₁, a second lens L₂, a third lens L₃and a fourth lens L₄, wherein the first lens L₁and the third lens L₃are aspheric lens, and the first lens L₁is a negative lens; the two doublet of the rear group lens G₂are formed by bonding a fifth lens L₅and a sixth lens L₆to form a first doublet C₁, and by bonding an eighth lens L₈, a ninth lens L₉and a tenth lens L₁₀to form a second doublet C₂, and the seventh lens L₇is an aspheric lens, the seventh lens L₇can also be an independent lens, or the seventh lens L₇can be bonded with the sixth lens L₆to make the fifth lens L₅, the sixth lens L₆and the seventh lens L₇form a first doublet C₁; the eleventh lens L₁₁is a single lens and is the last lens, but the present invention is not limited to such application.

TABLE 1

Refractive
Abbe

index
Number

Surface
Radius(mm)
Thickness(mm)
(Nd)
(Vd)

(MIRROR)
29.52
69.90

L1R1
−18.35
2.20
1.53
56.28

L1R2
15.54
1.60

L2R1
19.81
1.00
1.73
54.67

L2R2
10.47
1.96

L3R1
19.18
3.68
1.53
56.28

L3R2
14.91
2.52

L4R1
19.93
3.50
1.85
23.79

L4R2
−63.08
13.82

(APERTURE)
INF
0.20

L5R1
−53.47
3.00
1.70
41.14

L6R1
−4.82
0.60
1.80
46.57

L7R1
10.00
3.66
1.52
64.07

L7R2
−8.76
0.20

L8R1
19.93
3.80
1.50
81.59

L9R1
−8.18
0.60
1.85
23.79

L10R1
23.61
4.23
1.50
81.59

L10R2
−12.99
0.20

L11R1
55.19
3.18
1.92
18.90

L11R2
−20.91
3.50

TABLE 2

ASPH
MIRROR
1R₁
1R₂
3R₁
3R₂
7R₁
7R₂

Radius
29.52
−18.35
15.54
19.18
14.91
10.00
−8.76

Conic
−1.12
0.00
1.34
0.00
0.00
0.00
2.09

4TH
−1.34E−06
3.14E−04
5.16E−04
1.50E−03
1.07E−03
0.00E+00
3.54E−04

6TH
2.27E−09
−2.38E−06
−6.26E−06
−2.99E−05
−2.04E−05
0.00E+00
−6.11E−06

8TH
−1.74E−12
2.32E−08
−2.49E−07
5.03E−07
6.66E−07
0.00E+00
4.03E−06

10th
1.13E−15
−1.78E−10
7.85E−09
−7.50E−09
−2.16E−08
0.00E+00
−5.30E−07

12th
−4.24E−19
1.02E−12
−1.05E−10
6.76E−11
3.77E−10
0.00E+00
4.14E−08

14th
7.24E−23
−3.72E−15
7.19E−13
−2.79E−13
−3.34E−12
0.00E+00
−1.64E−09

16th
0.00E+00
6.49E−18
−2.09E−15
2.69E−16
1.21E−14
0.00E+00
2.74E−11

An aperture 40 arranged inside the lens group 10 and the center of the aperture 40 is defined as an origin O, define the axial direction as X axis X and the radial direction as Y axis Y to form a rectangular coordinate system B, the rectangular coordinate system B has a first quadrant B₁, a second quadrant B₂, a third quadrant B₃and a fourth quadrant B₄, and the projection optical system 60A has an optical axis 61 which coincided with the X axis X making the chief ray A₁of one of the optical paths A forms a chief ray A₁of a paraxial image height E₁at the part where image source IMA be near to the optical axis 61, the chief ray A₁of another one of the optical paths A forms a marginal ray A₂of an off-axis image height E₂at the part where image source IMA be far from the optical axis 61.

Referring to FIGS. 1D-1F, when the image source IMA and the image 30 are located in the second quadrant B₂and the reflector 20 is located in the fourth quadrant B₄, the chief ray A₁of the paraxial image height E₁intersects with the chief ray A₁of the off-axis image height E₂, then sequentially forming a first point P₁and a second point P₂, the first point P₁located at the origin O and the second point P₂is located in the first quadrant B₁, and the chef ray A₁of the optical path A intersects with the marginal ray A₂of the optical path A, and sequentially forming a third point P₃and a fourth point P₄, the third point P₃located at the fourth quadrant B₄and the fourth point P₄is located in the second quadrant B₂.

The projection optical system 60A set the first wave length λ₁, the second wave length λ₂, the third wave length λ₃as 0.450 um, 0.540 um and 0.630 um, and each of them can simulate different graphs illustrating the ray fan plot of FIGS. 1G-1L, and the same image source IMA can present different image height, 0.5830 mm, 0.8710 mm, 1.7420 mm, 2.6130 mm, 3.4840 mm, 4.3500 mm, and the mark ey, py, ex and px represents the lateral aberration of Y axis, the pupil distance of Y axis, the lateral aberration of X axis and the pupil distance of X axis, wherein the maximum scale the lateral aberration of Y axis and the lateral aberration of X are ±20.000 um, and the pupil distance of Y axis the pupil distance of X axis is a normalized ratio; The field curvature graph FIG. 1M and the distortion graph FIG. 1N has maximum field 4.355 mm; The lateral color aberration graph FIG. 10 has maximum field 4.355 mm; The vertical aberration graph FIG. 1P has pupil radius 0.3470 mm, with the above simulation curve and data can prove the projection optical system 60A maintain good image quality. Furthermore, as FIG. 1Q showing, between the reflector 20 and the image 30 include at least an optical element 50 for deflecting the optical path or correcting aberrations, but the present invention is not limited to such application.

In this embodiment, the Abbe number Vd of the 11^thlens of the rear group lens G₂that is closest to the image source IMA side is 18.9, the Nd thereof is 1.92, the Abbe number Vd is 18.9, and it complies the requirement of the projection optical system 60A that the Nd is 1.8-2.05, the Abbe number Vd is between 16-35; the Fno (F-number) of the projection optical system 60A is 1.8, it complies the requirement of the projection optical system 60A that the Fno (F-number) is between 1.6-3.2; moreover, in this embodiment, the width W of the image 30 is 1439, the value of the projection distance T from the reflector 20 to the image 30 is 360, so the projection ratio T/W is 0.25, thus conforms to the conditional formula of the projection ratio of the projection optical system: 0.16<T/W<0.3; the displacement d of a center point of the image source corresponding to the optical axis is 2.04, the short side h of the image source is 2.92, so 2d/h is 140%, thus conforms the requirement of the projection optical system 60A that 130%<2d/h<160%; moreover, in this embodiment, the focal length F1 of the reflector 20 is set as 14.76, the focal length F2 of the lens group 10 is set as 5.49, so F1/F2 is 2.69, thus conforms the requirement of the projection optical system 60A that 2.2<F1/F2<3.0; the maximum image height of the projection optical system 60A is 4.355, the projection ratio is 0.25, the Fno is 1.8, the ratio of IMH/TR/Fno is 9.67, thus conforms to the conditional formula 8<IMH/TR/Fno<11; and the maximum image height of the projection optical system 60A is 4.355, the distance T1 from the reflector 20 to the lens group 10 is 69.9, and the total length T2 of the lens group is 49.95, so the ratio of IMH*T1/T2 is 6.09, which conforms to the conditional formula 5<IMH*T1/T2<8. The first to fourth embodiment are having the same features above mentioned, therefore, they are technically interrelated and belong to a broad concept of invention, conform to the principle of unity, the only difference is the front group lens G₁and the second group lens G₂are slightly different.

Referring to the FIGS. 2A-2C, Table 3 and Table 4, the projection optical system 60B of the second embodiment has the front group lens G₁includes a first lens L₁, a second lens L₂, a third lens L₃and a fourth lens L₄, wherein the first lens L₁and the third lens L₃are aspheric lens, and the first lens L₁is a negative lens; the two doublet of the rear group lens G₂are formed by bonding a fifth lens L₅and a sixth lens L₆to form a first doublet C₁, and by bonding a seventh lens L₇, an eighth lens L₈and ninth lens L₉to form a second doublet C₂, and the sixth lens L₆are aspheric lens; the tenth lens L₁₀is a single lens and the last lens, but the present invention is not limited to such application.

TABLE 3

Refractive
Abbe

Radius
Thickness
index
number

Surface
(mm)
(mm)
(Nd)
(Vd)

(MIRROR)
29.52
71.35

L1R1
−18.35
2.20
1.53
56.28

L1R2
15.54
2.26

L2R1
19.81
1.00
1.73
54.67

L2R2
10.47
1.80

L3R1
19.18
3.68
1.53
56.28

L3R2
14.91
2.52

L4R1
19.93
3.50
1.85
23.79

L4R2
−63.08
13.96

(APERTURE)
INF
2.45

L5R1
702.62
0.60
1.80
46.57

L6R1
9.59
2.70
1.52
64.07

L6R2
−15.27
0.20

L7R1
34.80
3.45
1.50
81.59

L8R1
−6.77
0.60
1.85
23.79

L9R1
50.59
4.28
1.50
81.59

L9R2
−9.78
0.20

L10R1
75.14
3.10
1.92
18.90

L10R2
−20.00
3.50

TABLE 4

ASPH
MIRROR
1R₁
1R₂
3R₁
3R₂
6R₁
6R₂

Radius
29.52
−18.35
15.54
19.18
14.91
9.59
−15.27

Conic
−1.12
0.00
1.34
0.00
0.00
0.00
4.62

4TH
−1.34E−06
3.14E−04
5.16E−04
1.50E−03
1.07E−03
0.00E+00
2.64E−04

6TH
2.27E−09
−2.38E−06
−6.26E−06
−2.99E−05
−2.04E−05
0.00E+00
−2.73E−05

8TH
−1.74E−12
2.32E−08
−2.49E−07
5.03E−07
6.66E−07
0.00E+00
9.16E−06

10th
1.13E−15
−1.78E−10
7.85E−09
−7.50E−09
−2.16E−08
0.00E+00
−1.43E−06

12th
−4.24E−19
1.02E−12
−1.05E−10
6.76E−11
3.77E−10
0.00E+00
1.19E−07

14th
7.24E−23
−3.72E−15
7.19E−13
−2.79E−13
−3.34E−12
0.00E+00
−5.03E−09

16th
0.00E+00
6.49E−18
−2.09E−15
2.69E−16
1.21E−14
0.00E+00
8.51E−11

In second embodiment, the Abbe number Vd of the 10^thlens of the rear group lens G₂that is closest to the image source IMA side is 18.9, the Nd is 1.92, it complies the requirement of the projection optical system 60B that the Abbe number Vd is between 16-35 and the Nd is between 1.8-2.05; the Fno (F-number) of the projection optical system 60B is 1.8, it complies the requirement of the projection optical system 60B that the Fno (F-number) is between 1.6-3.2; moreover, in this embodiment, the width W of the image 30 is 664, the value of the projection distance T from the reflector 20 to the image 30 is 180, so the projection ratio T/W is 0.27, thus conforms to the conditional formula of the projection ratio of the projection optical system: 0.16<T/W<0.3; the displacement d of a center point of the image source corresponding to the optical axis is 2.04, the short side h of the image source is 2.92, so 2d/h is 140%, thus conforms the requirement of the projection optical system 60B that 130%<2d/h<160%; moreover, in this embodiment, the focal length F1 of the reflector 20 is set as 14.76, the focal length F2 of the lens group 10 is set as 5.68, so F1/F2 is 2.60, thus conforms the requirement of the projection optical system 60B that 2.2<F1/F2<3.0; the maximum image height of the projection optical system 60B is 4.355, the projection ratio is 0.27, the Fno is 1.8, the ratio of IMH/TR/Fno is 8.93, thus conforms to the conditional formula 8<IMH/TR/Fno<19; and the maximum image height of the projection optical system 60B is 4.355, the distance T1 from the reflector 20 to the lens group 10 is 71.35, and the total length T2 of the lens group is 48.5, so the ratio of IMH*T1/T2 is 6.41, which conforms to the conditional formula 5<IMH*T1/T2<8.

Referring to the FIGS. 3A-3C, Table 5 and Table 6, the projection optical system 60C of the third embodiment has the front group lens G₁includes a first lens L₁, a second lens L₂, a third lens L₃and a fourth lens L₄, wherein the first lens L₁and the third lens L₃are aspheric lens, and the first lens L₁is a negative lens; the two doublet of the rear group lens G₂are formed by bonding a fifth lens L₅, a sixth lens L₆and the seventh lens L₇to form a first doublet C₁, and by bonding an eighth lens L₈, a ninth lens L₉and a tenth lens L₁₀to form a second doublet C₂; the eleventh lens L₁₁is a single lens and the last lens, but the present invention is not limited to such application.

TABLE 5

Refractive
Abbe

Radius
Thickness
index
Number

Surface
(mm)
(mm)
(Nd)
(Vd)

(MIRROR)
23.58
63.19

L1R1
−13.86
2.00
1.51
56.32

L1R2
17.97
2.45

L2R1
27.31
1.00
1.80
46.57

L2R2
9.56
0.84

L3R1
9.79
3.44
1.51
56.32

L3R2
7.80
2.80

L4R1
15.85
2.60
1.85
23.78

L4R2
−62.60
11.88

(APERTURE)
INF
2.66

L5R1
72.14
1.82
1.57
42.81

L6R1
−5.99
0.60
1.83
37.21

L7R1
13.74
2.12
1.49
70.44

L7R2
−9.67
0.20

L8R1
29.60
2.47
1.50
81.61

L9R1
−8.08
0.60
1.85
23.78

L10R1
145.99
3.05
1.50
81.61

L10R2
−9.91
0.20

L11R1
46.17
2.18
1.92
18.90

L11R2
−23.64
3.50

TABLE 6

ASPH
MIRROR
L1R1
L1R2
L3R1
L3R2

Radius
23.58
−13.86
17.97
9.79
7.80

Conic
−1.23
0.00
0.07
0.00
0.00

4TH
−3.02E−06
7.76E−04
1.83E−03
2.59E−03
1.44E−03

6TH
6.54E−09
−2.91E−05
−8.19E−05
−1.16E−04
−6.84E−05

8TH
−5.97E−12
7.33E−07
1.63E−06
5.03E−06
5.17E−06

10th
3.83E−15
−1.11E−08
−2.10E−08
−1.71E−07
−2.79E−07

12th
−1.38E−18
9.97E−11
1.92E−10
3.48E−09
7.67E−09

14th
2.27E−22
−4.93E−13
−1.17E−12
−3.80E−11
−1.06E−10

16th
0.00E+00
1.03E−15
3.50E−15
1.72E−13
5.94E−13

In third embodiment, the Abbe number Vd of the 11^thlens of the rear group lens G₂that is closest to the image source IMA side is 18.9 and the Nd is 1.92, it complies the requirement of the projection optical system 60C that the Abbe number Vd is between 16-35 and the Nd is 1.8-2.5; the Fno (F-number) of the projection optical system 60C is 2.8, it complies the requirement of the projection optical system 60C that the Fno (F-number) is between 1.6-3.2; moreover, in this embodiment, the width W of the image 30 is 1774, the value of the projection distance T from the reflector 20 to the image 30 is 336, so the projection ratio T/W is 0.19, thus conforms to the conditional formula of the projection ratio of the projection optical system: 0.16<T/W<0.3; the displacement d of a center point of the image source corresponding to the optical axis is 2.11, the short side h of the image source is 2.92, so 2d/h is 145%, thus conforms the requirement of the projection optical system 60B that 130%<2d/h<160%; moreover, in this embodiment, the focal length F1 of the reflector 20 is set as 11.79, the focal length F2 of the lens group 10 is set as 4.83, so F1/F2 is 2.44, thus conforms the requirement of the projection optical system 60C that 2.2<F1/F2<3.0; the maximum image height of the projection optical system 60C is 4.413, the projection ratio is 0.19, the Fno is 2.8, the ratio of IMH/TR/Fno is 8.32, thus conforms to the conditional formula 8<IMH/TR/Fno<19; and the maximum image height of the projection optical system 60C is 4.413, the distance T1 from the reflector 20 to the lens group 10 is 63.19, and the total length T2 of the lens group is 42.91, so the ratio of IMH*T1/T2 is 6.50, which conforms to the conditional formula 5<IMH*T1/T2<8.

Referring to the FIGS. 4A-4C, Table 7 and Table 8, the projection optical system 60D of the fourth embodiment has the front group lens G₁includes a first lens L₁, a second lens L₂, a third lens L₃and a fourth lens L₄, wherein the second lens L₂and the fourth lens L₄are aspheric lens, and the second lens L₂is a negative lens; the two doublet of the rear group lens G₂are formed by bonding a fifth lens L₅and a sixth lens L₆to form a first doublet C₁, by bonding a seventh lens L₇and an eighth lens L₈, to form a second doublet C₂, by bonding a ninth lens L₉, a tenth lens L₁₀and an eleventh lens L₁₁to form a third doublet C₃, by bonding a twelfth lens L₁₂, a thirteenth lens L₁₃and a fourteenth lens L₁₄to form a fourth doublet C₄, and the fifteenth lens L₁₅and the sixteenth lens L₁₆are aspheric lens,; the sixteenth lens L₁₆is the last lens, but the present invention is not limited to such application.

TABLE 7

Refractive
Abbe

index
Number

Surface
Radius
Thickness
(Nd)
(Vd)

(MIRROR)
37.58
78.71

L1R1
−161.75
2.50
1.92
18.90

L1R2
73.72
4.92

L2R1
−47.73
4.00
1.54
55.98

L2R2
25.47
14.39

L3R1
−153.61
6.41
1.80
39.64

L3R2
−41.03
2.00

L4R1
−71.64
3.24
1.54
55.98

L4R2
−34.89
12.09

L5R1
26.78
1.30
1.88
40.81

L6R1
9.78
4.52
1.67
33.05

L6R2
151.86
2.18

L7R1
−15.43
1.30
1.83
42.71

L8R1
16.13
3.66
1.70
30.05

L8R2
−14.82
6.70

(APERTURE)
INF
2.81

L9R1
223.31
2.87
1.49
70.44

L10R1
−12.88
1.30
1.91
35.25

L11R1
657.70
3.87
1.50
81.61

L11R2
−11.64
0.40

L12R1
155.29
4.28
1.49
70.44

L13R1
−13.45
1.30
1.88
39.22

L14R1
36.41
4.90
1.50
81.61

L14R2
−23.32
0.20

L15R1
42.35
4.46
1.50
81.61

L15R2
−51.92
0.20

L16R1
58.30
3.42
1.90
31.31

L16R2
−109.88
6.20

TABLE 8

ASPH
MIRROR
L2R1
L2R2
L4R1
L4R2

Radius
37.58
−47.73
25.47
−71.64
−34.89

Conic
−5.22
0.00
0.00
0.00
0.00

4TH
5.96E−06
3.61E−06
−9.93E−05
2.31E−06
1.82E−05

6TH
−3.66E−09
2.65E−07
5.83E−07
−3.73E−08
−7.18E−08

8TH
1.80E−12
−1.27E−09
−2.47E−09
1.77E−09
1.91E−09

10th
−5.55E−16
3.00E−12
5.72E−12
−1.05E−11
−1.16E−11

12th
9.83E−20
−3.65E−15
−6.93E−15
2.36E−14
2.76E−14

14th
−7.25E−24
1.84E−18
3.42E−18
−1.87E−17
−2.36E−17

16th
0.00E+00
0.00E+00
0.00E+00
0.00E+00
0.00E+00

In fourth embodiment, the Abbe number Vd of the 11^thlens of the rear group lens G₂that is closest to the image source IMA side is 31.31 and the Nd is 1.90, it complies the requirement of the projection optical system 60D that the Abbe number Vd is between 16-35 and the Nd is between 1.8-2.05; the Fno (F-number) of the projection optical system 60D is 2.4, it complies the requirement of the projection optical system 60D that the Fno (F-number) is between 1.6-3.2; moreover, in this embodiment, the width W of the image 30 is 1994, the value of the projection distance T from the reflector 20 to the image 30 is 400, so the projection ratio T/W is 0.20, thus conforms to the conditional formula of the projection ratio of the projection optical system: 0.16<T/W<0.3; the displacement d of a center point of the image source corresponding to the optical axis is 4.08, the short side h of the image source is 5.83, so 2d/h is 140%, thus conforms the requirement of the projection optical system 60D that 130%<2d/h<160%; moreover, in this embodiment, the focal length F1 of the reflector 20 is set as 18.79, the focal length F2 of the lens group 10 is set as 7.73, so F1/F2 is 2.43, thus conforms the requirement of the projection optical system 60D that 2.2<F1/F2<3.0; the maximum image height of the projection optical system 60D is 8.709, the projection ratio is 0.20, the Fno is 2.4, the ratio of IMH/TR/Fno is 18.09, thus conforms to the conditional formula 8<IMH/TR/Fno<19; and the maximum image height of the projection optical system 60D is 8.709, the distance T1 from the reflector 20 to the lens group 10 is 78.71, and the total length T2 of the lens group is 99.22, so the ratio of IMH*T1/T2 is 6.91, which conforms to the conditional formula 5<IMH*T1/T2<8.

With the feature disclosed above, the projection optical systems 60A-60D of first to forth embodiments, the table 9 summarizes the focal length F1 of the reflector 20, the focal length F2 of the lens group 10, the maximum image height of the projection optical system, the throw ratio TR, the Fno of the projection optical system, the distance T1 from the reflector 20 to the lens group 10, the total length T2 of the lens group, the projection distance T, the width W of the image 30, the displacement amount d, and the short side h of the image source, and adjusts to a certain matching range, thereby promotes the effect of the stabilizing quality of the image 30. Furthermore, through the matching of each lens to meet the requirements of various optical conditions, the projection optical systems 60A-60D will achieve the best optical performance, including a). The ratio of F1/F2 is between 2.2-3.0(F1 is the focal length of the reflector, F2 is the focal length of the lens group), which will optimize various aberrations and external size; b). The ratio of IMH/TR/Fno is between 8-19 (IMH is the largest image height, TR is the throw ratio, Fno is the F-number), it will optimize the resolution, tolerance sensitivity and cost performance; c). The ratio of IMH*T1/T2 is between 5-8 (IMH is the maximum image height , T1 is the distance from the reflector to the lens group, and T2 is the total length of the lens group), then the resolution and the optical path interference allowance will be optimized.

TABLE 9

Embodiment
Embodiment
Embodiment
Embodiment

1
2
3
4

F1
14.76
14.76
11.79
18.79

F2
5.49
5.68
4.83
7.73

Image
4.355
4.355
4.413
8.709

height(IMH)

TR(T/W)
0.25
0.27
0.19
0.20

F-number
1.8
1.8
2.8
2.4

(Fno)

T1
69.9
71.35
63.19
78.71

T2
49.95
48.5
42.91
99.22

T
360
180
336
400

W
1439
664
1774
1994

d
2.04
2.04
2.11
4.08

h
2.92
2.92
2.92
5.83

F1/F2
2.69
2.60
2.44
2.43

IMH/TR/Fno
9.67
8.93
8.32
18.09

IMH*T1/T2
6.09
6.41
6.50
6.91

2 d/h
140%
140%
145%
140%

With the features of the embodiments disclosed above, the present invention continues to develop and improve the numerical values such as focal length, maximum image height, projection ratio, F-number (Fno), the present invention are designed to have better optical effect compared with the lens patent of the prior art, the projection optical system of the present invention not only has differences, but also can take into account the image quality when the projection distance is shortened, so that the projection configuration can be adjusted to the optimum, so as to obtain a good optical effect.

Although particular embodiment of the invention has 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.

	Number	Date	Country
Parent	17106747	Nov 2020	US
Child	17985269		US

PROJECTION OPTICAL SYSTEM WITH A CONCAVE REFLECTOR IN THE PROJECTION LENS

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Continuation in Parts (1)